Ergonomic Risk Prioritization of Work-Related Musculoskeletal Disorders in Lead-Acid Battery Manufacturing: A Cross-Sectional and Observational Study

Ergonomic Risk Prioritization of Work-Related Musculoskeletal Disorders in Lead-Acid Battery Manufacturing: A Cross-Sectional and Observational Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Ergonomic Risk Prioritization of Work-Related Musculoskeletal Disorders in Lead-Acid Battery Manufacturing: A Cross-Sectional and Observational Study Ruoyu Zhang, Zhengmin Yu, Renwei He, Dan Chen, Qimeng Tang, Ling Li, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8654310/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Objectives : This study aimed to investigate the prevalence and distribution of Work-related musculoskeletal disorders (WMSDs) among lead-acid battery manufacturing workers and to identify high-risk tasks and body regions through integrated epidemiological and ergonomic assessments, thereby establishing priorities for ergonomic intervention. Methods: We conducted a cross-sectional survey among 2,418 frontline workers from 10 lead–acid battery manufacturing enterprises in Jiangsu Province, China, using the Chinese Musculoskeletal Questionnaire (CMQ). Multivariable logistic regression was used to examine individual and work-related factors associated with WMSDs. Key production tasks were additionally assessed using video-based observation, with ergonomic hazards screened by the Swedish ergonomic hazard identification method and postural load quantified using the Rapid Upper Limb Assessment (RULA). Results: The overall 12-month prevalence of WMSDs was 51.61%. The lower back and wrist/hand were the most frequently affected regions, followed by the shoulder and neck, with higher neck and shoulder prevalence among female workers. Manual handling of heavy loads and highly repetitive operations were associated with increased odds of both low back and wrist/hand WMSDs, whereas adequate rest time and physical exercise showed protective associations. Using the Swedish checklist, hazards were most frequently identified in the neck/shoulders/upper back (34/36 positions), upper limbs (29/36), and lower back (28/36). RULA classified 22/36 (61.11%) job positions as action levels III–IV, including 12/36 (33.33%) requiring immediate changes, indicating substantial postural load in key tasks. Conclusions: WMSDs impose a substantial burden in lead–acid battery manufacturing. Combining symptom surveillance with observational ergonomic assessment helps identify and prioritize high-risk tasks for targeted intervention, providing actionable evidence for workplace redesign and occupational health risk management in labor-intensive manufacturing settings. work-related musculoskeletal disorders lead–acid battery manufacturing ergonomic risk factors Rapid Upper Limb Assessment Swedish ergonomic hazard identification method occupational health Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Work-related musculoskeletal disorders (WMSDs) constitute a major occupational health concern worldwide and represent a substantial burden in manufacturing industries. Prolonged exposure to adverse ergonomic conditions—such as repetitive movements, awkward or sustained postures, and excessive physical load—has been consistently identified as a key contributor to the development of WMSDs [ 1,2 ] . According to the Global Burden of Disease (GBD) Study, musculoskeletal disorders affect more than 1.7 billion people globally and represent one of the leading causes of years lived with disability (YLDs), with low back pain consistently ranking as the top contributor across most age groups and regions 3 , 4 . From an occupational health perspective, WMSDs account for approximately 30–50% of all reported work-related health problems in industrialized countries, highlighting their dominant role among occupational diseases 5 , 6 . In manufacturing settings, workers are frequently exposed to combinations of repetitive tasks, high work pace, and limited opportunities for postural variation, which promote the chronic accumulation of biomechanical load. Unlike acute occupational injuries, WMSDs typically develop insidiously and may progress from transient discomfort to persistent pain, functional limitation, and reduced work ability. These conditions are closely associated with sickness absence, decreased productivity, and premature exit from the workforce, thereby imposing substantial socioeconomic costs 2 , 7 . Epidemiological evidence from manufacturing industries further supports this elevated risk. A recent systematic review and meta-analysis focusing on the automobile manufacturing industry in China reported a 12-month WMSDs prevalence of 53.1%, with the lower back, neck, and shoulders being the most frequently affected body regions. Similar prevalence patterns have been observed in other manufacturing sectors, including electronics assembly and emerging manufacturing industries, where reported WMSDs prevalence ranged from 28.6% to over 40%, depending on job type and ergonomic exposure intensity 8 . These findings indicate that WMSDs remain a pervasive and unresolved occupational health issue in modern manufacturing systems. However, existing studies on WMSDs in manufacturing industries have predominantly relied on questionnaire-based surveys to describe symptom prevalence and associated risk factors 9 – 11 . While such approaches provide valuable epidemiological information, they often lack task-specific ergonomic assessment, thereby offering limited guidance for identifying and prioritizing high-risk operations for targeted intervention. Evidence therefore remains insufficient regarding which specific tasks contribute most to ergonomic risk in battery manufacturing environments, particularly in labor-intensive production lines.Another important methodological limitation in WMSDs research is the reliance on self-reported symptoms as a proxy for ergonomic exposure. Although symptom surveys are essential for identifying affected body regions and estimating disease prevalence, they do not necessarily reflect actual biomechanical load or postural risk. Workers performing different tasks may report similar symptoms despite markedly different ergonomic demands, highlighting the potential discrepancy between perceived discomfort and objective exposure. Consequently, there is increasing recognition of the need to integrate epidemiological approaches with observational ergonomic assessment methods. Structured ergonomic hazard identification tools, such as the Swedish ergonomic risk identification method, are designed to systematically screen task-related risk factors across multiple body regions, including the neck, upper limbs, trunk, and lower extremities, by focusing on posture, repetition, force, and work organization. These checklist-based approaches allow comprehensive identification of unfavorable ergonomic conditions at the workstation and task level. In addition, the Rapid Upper Limb Assessment (RULA) method, originally developed by McAtamney and Corlett, is a widely used observational tool for evaluating postural load and physical stress affecting the neck, trunk, and upper limbs during work activities. As a systematic observational method, RULA has been extensively applied in manufacturing and assembly settings to identify high-risk tasks, quantify postural risk levels, and support ergonomic risk prioritization and intervention planning 12 , 13 . Against this background, the present study aimed to: (1) describe the prevalence and distribution of WMSDs among workers in lead-acid battery manufacturing enterprise; (2) identify task-related ergonomic hazards across key job positions using a structured ergonomic hazard identification approach; and (3) prioritize high-risk tasks based on RULA scores. By integrating epidemiological data with observational ergonomic assessment, this study seeks to provide evidence-based guidance for task-specific ergonomic interventions and to support occupational health risk management in labor-intensive manufacturing settings. 2. Methods 2.1 Study setting and participants The investigation was conducted in a prefecture-level city in Jiangsu Province, China, where lead–acid battery manufacturing is highly concentrated. A total of 10 lead–acid battery manufacturing enterprises of varying production scales were included.The field survey was carried out between May and July 2024.Several of the investigated enterprises were subsidiaries of nationally recognized lead–acid battery manufacturers, featuring complete production chains and stable manufacturing capacity. Therefore, the selected enterprises were considered representative of lead–acid battery manufacturing in eastern China. The study population consisted of frontline production workers employed in the selected lead–acid battery manufacturing enterprises. Workers were eligible for inclusion if they met the following criteria:(1) aged 18 years or older; (2) had at least one year of work experience in lead–acid battery manufacturing.Workers were excluded if they were pregnant, had physical disabilities, or reported musculoskeletal disorders caused by non-occupational factors, such as acute trauma or chronic metabolic diseases. 2.2 Sample size determination The required sample size was estimated using standard methods for cross-sectional studies. In the absence of prior prevalence data on WMSDs among lead-acid battery manufacturing workers, the expected prevalence was conservatively set at 0.50. With a 95% confidence level and an absolute precision of 2.19%, the minimum sample size was estimated at approximately 2,203 participants. To account for potential non-response, the target sample size was increased by 10%. To ensure representativeness, at least 30% of frontline workers from each enterprise were surveyed. 2.3 Questionnaire Survey The epidemiological cross-sectional survey was conducted using the electronic version of the Chinese Musculoskeletal Disorders Questionnaire(CMQ) provided by the Occupational Health and Poison Control Institute of the Chinese Center for Disease Control and Prevention. This questionnaire has demonstrated good reliability and validity. Participants completed the questionnaire on site in small groups, with trained investigators providing standardized instructions.The questionnaire consisted of three sections. The first section collected basic demographic and personal information, including sex, age, height, weight, job type, years of service, educational level, and medical history. The second section addressed musculoskeletal symptoms, covering nine body regions—neck, shoulder, upper back, lower back (lumbar), elbow, wrist/hand, hip/leg, knee, and ankle/foot—and recorded the occurrence, duration, and frequency of pain or discomfort over the past 12 months. The third section focused on work-related factors, including work type, organization of tasks, break schedules, and working postures. Participants accessed the questionnaire by scanning a QR code, and responses were submitted electronically, directly uploading data to an online database for analysis. 2.4 Evaluation of Work-Related Musculoskeletal Disorders WMSDs in this study were evaluated following the guidelines of the National Institute for Occupational Safety and Health (NIOSH). WMSDs were considered present if participants reported discomfort-including pain, stiffness, burning, numbness, or tingling-while fulfilling all of the following conditions: (1) symptoms occurred within the previous 12 months; (2) symptoms started after beginning the current job; (3) the affected area was not influenced by prior accidents or acute injuries; and (4) symptoms occurred at least once per month or persisted for more than one week in total. The prevalence of WMSDs in a specific body region was calculated as the number of affected individuals divided by the total number of participants, whereas overall WMSDs prevalence was defined as the proportion of participants reporting symptoms in any body region. This study adopted a cross-sectional observational ergonomic assessment design to investigate WMSDs risks in lead–acid battery manufacturing. Field investigations were conducted in 10 lead–acid battery manufacturing enterprises located in Jiangsu Province, China. These enterprises varied in production scale, level of automation, and organizational management, but shared comparable core manufacturing processes. 2.5 Video Recording of Key Work Tasks During the on-site investigation, trained investigators accompanied the enterprise safety officers to various production workshops to conduct video recordings of key work tasks and job categories. Mobile phones or tablet devices were used to record workers’ task performance without interfering with their normal work activities. For each workstation or job type, video recordings captured the workers from the left side, right side, and front view. At least three work cycles were observed per workstation, with each video lasting approximately 2–5 min.Additionally, for each job type, task performance was recorded for a minimum of three different workers to ensure representativeness. To optimize data collection efficiency and minimize disruption to routine production activities, video recording was conducted concurrently with the questionnaire survey. Dedicated team members were responsible for video acquisition throughout the field investigation. All video recordings were collected between May and July 2024. 2.6 Swedish ergonomic hazard identification Ergonomic risk factors were assessed using the Swedish ergonomic hazard identification checklist. The validated Chinese version was used to screen potentially hazardous body regions and related ergonomic risk factors during work tasks. The checklist covers five body regions: (1) neck, shoulders, and upper back; (2) elbows, forearms, and wrists; (3) feet; (4) knees and thighs/hips; and (5) lower back, comprising 17 items in total. Video recordings of each workstation/task were reviewed repeatedly and coded against the 17 checklist items. The assessment followed a standardized procedure: (1) reviewing videos to identify body regions potentially at risk; (2) mapping the identified regions to relevant checklist items to determine specific hazards; (3) marking applicable items on the checklist; and (4) recording additional contextual factors that may increase musculoskeletal strain, including limited ability to pause work, low task/workspace autonomy, time pressure or psychosocial stress, abnormal/unexpected work conditions, adverse environmental exposures (e.g., cold/heat/noise), and rapid movements, shaking, or vibration. Where discrepancies occurred, assessors discussed the recordings and reached consensus. 2.7 Ergonomic risk assessment using RULA The Rapid Upper Limb Assessment (RULA) method was used to evaluate the level of ergonomic risk associated with each key task. The validated Chinese version of RULA was applied.RULA divides the body into two groups(Group A: upper arm, lower arm, and wrist;Group B: neck, trunk, and legs).Postural scores were determined based on observed working postures, and additional scores were assigned according to muscle use and external load. Final RULA scores range from 1 to 7, corresponding to four action levels:Level 1 (scores 1–2): acceptable risk;Level 2 (scores 3–4): further investigation required;Level 3 (scores 5–6): investigation and changes needed soon;Level 4 (score 7): investigation and changes required immediately.To account for inter-individual variability, three workers per task were independently evaluated. Two trained researchers conducted RULA assessments independently, and the mean score rounded to the nearest integer was used as the final RULA score for each task. 2.8 Quality control All investigators received standardized training prior to data collection. During the survey, unified instructions were provided, and questionnaires were completed independently by participants under on-site supervision.Questionnaires were checked on site for completeness and logical consistency. 2.9 Statistical Analysis Statistical analyses were performed using IBM SPSS Statistics version 23.0 (network licensed edition).Continuous variables were expressed as mean ± standard deviation, and categorical variables as frequencies and percentages. The 12-month prevalence of work-related musculoskeletal disorders (WMSDs) was calculated overall and stratified by sex, body region, and production section.Group differences in WMSDs prevalence were assessed using the chi-square (χ²) test. Multivariable logistic regression analyses were conducted to identify factors associated with low back and wrist WMSDs. Ergonomic hazards identified using the Swedish ergonomic hazard identification method and RULA scores were summarized descriptively. All tests were two-sided, and P < 0.05 was considered statistically significant. 3. Results 3.1 Demographic and occupational characteristics A total of 2,609 frontline workers from 10 lead–acid battery manufacturing enterprises in Jiangsu Province were initially surveyed. In each enterprise, the number of participants accounted for more than 30% of the frontline workforce. After excluding 191 invalid questionnaires, 2,418 valid questionnaires were included in the final analysis, yielding a response rate of 92.68%. The final sample size exceeded the estimated minimum requirement and was considered sufficient for statistical analysis. Among the included participants, 1,335 were male and 1,083 were female. The mean age of the workers was 41.55 ± 7.65 years, and the mean duration of employment was 4.45 ± 3.74 years. For male workers, the mean height was 171.45 ± 6.27 cm, mean body weight was 70.83 ± 11.21 kg, and mean body mass index (BMI) was 24.06 ± 3.50 kg/m². Female workers had a mean height of 159.85 ± 5.80 cm, mean body weight of 59.61 ± 9.58 kg, and mean BMI of 23.32 ± 3.56 kg/m². Regarding educational attainment, 78.33% of the participants had completed junior middle school or below, 18.03% had senior high school or vocational education, and 3.64% had attained college level or higher education. With respect to physical exercise habits, 56.74% of the workers reported no regular physical exercise, 32.71% reported occasional exercise, and 10.55% reported regular physical exercise(Table 1 ). Table 1 Demographic characteristics of lead-acid battery manufacturing workers Demographic characteristics Overall Male Female N(%) N(%) N(%) Age < 35 561(23.2) 334(13.81) 227(9.39) 35 ~ 44 1156(47.81) 597(24.69) 559(23.12) ≥ 45 701(28.99) 404(16.71) 297(12.28) BMI(kg/m 2 ) < 18.5 74(3.06) 32(1.32) 42(1.74) 18.5 ~ 23.9 1300(53.76) 650(26.88) 650(26.88) 24.0 ~ 27.9 831(34.37) 511(21.13) 320(13.23) ≥ 28.0 213(8.81) 142(5.87) 71(2.94) Years of employment 1 ~ 5 1512(62.53) 842(34.82) 670(27.71) 5 ~ 9 581(24.03) 307(12.7) 274(11.33) ≥ 10 325(13.44) 186(7.69) 139(5.75) Dominant hand Left 136(5.62) 92(3.8) 44(1.82) Right 2282(94.38) 1243(51.41) 1039(42.97) Education Junior middle school or below 1894(78.33) 941(38.92) 953(39.41) Senior high school or vocational school 436(18.03) 326(13.48) 110(4.55) College or above 88(3.64) 68(2.81) 20(0.83) Marital status Unmarried 43(1.78) 29(1.2) 14(0.58) married 2338(96.69) 1281(52.98) 1057(43.71) Other (divorced or widowed) 37(1.53) 25(1.03) 12(0.5) Monthly income (RMB) 5000 2078(85.94) 1176(48.64) 902(37.3) 3.2 Prevalence and anatomical distribution of WMSDs A total of 2,418 frontline workers from lead-acid battery manufacturing enterprises were included in the analysis. The overall 12-month prevalence of work-related musculoskeletal disorders (WMSDs) was 51.61%.The most frequently affected body regions were the lower back, hand/wrist, shoulder, neck, and thigh/hip (Table 2 ). Among these regions, lower back symptoms showed the highest prevalence. Female workers reported a notably higher prevalence of neck and shoulder symptoms compared with male workers, whereas no substantial sex differences were observed for lower back or hand/wrist disorders.These findings indicate that WMSDs are highly prevalent in lead-acid battery manufacturing, with symptoms predominantly concentrated in the trunk and upper extremities(Table 2 ). Table 2 Prevalence of WMSDs by Body Region among Lead-Acid Battery Manufacturing Workers Body region Overall Male Female χ² P N(%) N(%) N(%) Total 1248(51.61) 656(49.14) 592(54.66) 7.31 0.01 Lower back 471(19.48) 264(10.92) 207(8.56) 0.17 0.68 Wrist/Hand 392(16.21) 201(8.31) 191(7.90) 2.93 0.09 Shoulder 315(13.03) 128(5.29) 187(7.73) 31.12 < 0.001 Neck 283(11.70) 91(3.76) 192(17.73) 68.90 < 0.001 Thigh/Hip 274(11.33) 141(10.56) 133(12.28) 1.76 0.19 Elbow 135(5.58) 76(3.14) 59(2.44) 0.07 0.79 Ankle/Foot 120(4.96) 60(2.48) 60(2.48) 1.39 0.24 Knee 78(3.23) 40(1.65) 38(1.57) 0.50 0.48 Upper back 60(2.48) 27(1.12) 33(1.36) 2.59 0.11 P values were calculated using the chi-square test. Percentages in the Overall column were calculated using the total sample size (N = 2418) as the denominator; percentages in the Male and Female columns were calculated using the male (N = 1335) and female (N = 1083) subgroups as denominators, respectively. Bars represent the prevalence of WMSDs in males and females. Asterisks indicate statistically significant differences between sexes ( P < 0.05). 3.3 Prevalence of WMSDs across Different Production Sections in Lead-acid Battery Manufacturing The prevalence of WMSDs varied across production sections in the lead-acid battery manufacturing process (section-specific analyses included 2,393 workers; 25 workers with mixed duties across sections were not included in this stratified analysis). Among all sections, the highest prevalence was observed in packaging (63.36%), followed by assembly (51.53%) and charging/formation (50.00%).Regarding specific body regions, the top three affected areas in the grid casting section were the lower back, shoulders, and thighs/buttocks; in the plate processing section, they were the lower back, hands/wrists, and thighs/buttocks; in the assembly and charging/formation sections, the most affected regions were the hands/wrists, lower back, and shoulders; in the packaging section, the lower back, hands/wrists, and neck were most frequently affected. Statistically significant differences in WMSDs prevalence among sections were observed for the lower back, hands/wrists, neck, and thighs/buttocks ( P < 0.05) (Table 3 ). Table 3 Prevalence of WMSDs by Body Region in Different Production Sections Production Section N Total WMSDs Neck Shoulder Upper Back Lower Back Elbow Hand/ Wrist Thigh/ Buttock Knee Ankle/Foot Grid Casting 273 107(39.19) 19(6.96) 27(9.89) 4(1.47) 45(16.48) 11(4.03) 12(4.40) 23(8.42) 6(2.20) 19(6.96) Plate Processing 482 239(49.59) 49(10.17) 58(12.03) 6(1.24) 100(20.76) 22(4.56) 72(14.94) 55(11.41) 14(2.90) 19(3.94) Assembly 925 476(51.53) 107(10.94) 116(11.27) 26(2.74) 166(16.08) 57(6.13) 172(17.83) 98(10.72) 31(3.17) 38(3.83) Charging/ Formation 497 249(50.00) 70(13.25) 70(14.66) 13(2.61) 99(18.27) 23(4.22) 79(15.66) 53(10.24) 18(3.21) 26(5.02) Packaging 199 127(63.32) 36(18.09) 34(16.08) 10(5.53) 56(27.64) 18(8.04) 46(24.21) 35(18.59) 7(3.52) 14(6.53) Others 42 25(60.47) 2(4.65) 10(23.26) 1(2.33) 5(11.63) 4(9.30) 11(27.91) 6(13.95) 2(4.65) 4(9.30) Total 2418 1223(50.58) 283(11.70) 315(13.03) 60(2.48) 471(19.48) 135(5.58) 392(16.21) 274(11.33) 78(3.23) 120(4.96) χ 2 29.979 19.604 10.678 9.986 14.558 9.410 42.601 11.214 1.752 8.546 P < 0.001 < 0.001 0.058 0.076 0.012 0.094 < 0.001 0.047 0.882 0.129 The color scale represents the prevalence (%) of WMSDs. Darker colors indicate higher prevalence, highlighting body regions and production sections with increased ergonomic risk. 3.4 Multivariable Logistic Regression Analysis of Low Back and Wrist WMSDs Multivariable logistic regression was used to identify factors associated with low back and wrist WMSDs. For low back WMSDs, adequate rest time (OR = 0.472, 95% CI: 0.363–0.615) and physical exercise (regular: OR = 0.579, 95% CI: 0.370–0.906; occasional: OR = 0.642, 95% CI: 0.495–0.833) were protective. Increased odds were observed for occasional smoking (OR = 1.727, 95% CI: 1.147–2.603), fair self-rated health (OR = 2.108, 95% CI: 1.624–2.737), manual handling of loads > 5 kg per lift (OR = 1.828, 95% CI: 1.374–2.432), highly repetitive operations (OR = 1.411, 95% CI: 1.076–1.851), frequent overtime (OR = 1.350, 95% CI: 1.055–1.727), and cold/temperature-fluctuating environments (OR = 1.560, 95% CI: 1.042–2.335). Poor self-rated health (OR = 2.222, 95% CI: 0.579–8.521) and prolonged kneeling/squatting (OR = 1.957, 95% CI: 0.966–3.966) showed positive but non-significant associations. For wrist WMSDs, employment duration ≥ 10 years (OR = 0.529, 95% CI: 0.349–0.801), regular exercise (OR = 0.577, 95% CI: 0.344–0.966), frequent smoking (OR = 0.485, 95% CI: 0.356–0.662), and adequate rest time (OR = 0.590, 95% CI: 0.445–0.784) were protective, whereas prolonged wrist flexion (OR = 1.417, 95% CI: 1.092–1.839), heavy loads > 5 kg (OR = 1.538, 95% CI: 1.136–2.081), very heavy loads > 20 kg (OR = 1.509, 95% CI: 1.135–2.006), and sustained pinching/gripping (OR = 1.860, 95% CI: 1.253–2.760) increased the odds. Figure 3 summarizes the site-specific patterns; full outputs are provided in Supplementary Tables S1–S2. Forest plot illustrating adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from multivariable logistic regression analyses examining associations between individual and occupational factors and the occurrence of low back and wrist WMSDs among lead-acid battery manufacturing workers. Black squares indicate low back WMSDs, and grey circles indicate wrist WMSDs. The vertical dashed line represents the null value (OR = 1). 3.5 Identification Results of Hazardous Factors in Key Work Positions Based on the checklist items of the Swedish ergonomic hazard identification method, hazards were assessed across five body regions in 36 job positions. Adverse ergonomic factors were identified to varying degrees in all five body regions across the 36 job positions. Specifically, the neck, shoulders, and upper back were affected in 34 job positions; the elbows, forearms, and wrists were involved in 29 job positions. For the lower limbs, 14 job positions exhibited adverse factors in the feet, while 15 job positions showed issues in the knees and hips, primarily related to “working in a standing posture without sitting or support” or “restricted workspace or limited material handling.” Additionally, the lumbar region was affected in 28 job positions. Details are provided in Supplement Table 2 . The distribution of ergonomic hazards across tasks and body regions is illustrated in Fig. 4 . The body map illustrates the distribution of ergonomic hazards identified across five major body regions based on the Swedish ergonomic hazard identification checklist. Color intensity reflects the number of job positions in which ergonomic hazards were identified for each body region, with darker colors indicating a higher prevalence across job positions. 3.6 RULA-based risk levels and task prioritization RULA scores for the 36 job positions in lead-acid battery manufacturing ranged from 1 to 7, corresponding to risk Levels I to IV. Among these positions, 2 job positions (5.56%) were classified as Level I, 12 positions (33.33%) as Level II, 10 positions (27.78%) as Level III, and 12 positions (33.33%) as Level IV. According to RULA guidelines, both Level III and Level IV indicate the need for ergonomic interventions. Level III represents job positions where further investigation and corrective actions are required, including ball milling in the grid casting process; coating (weighing) and wrapping in the plate processing process; cover sealing and component installation in the assembly process; acid filling, charging, and battery testing in the formation process; component installation in the packaging process; as well as auxiliary positions such as material handling (cart pushing and pulling). Level IV indicates job positions requiring urgent ergonomic interventions. These positions mainly included negative plate die casting and plate casting in the grid casting process; paste mixing, slicing (upper and lower plate), and coating (lower plate) in the plate processing process; terminal welding and battery hoisting in the assembly process; tank unloading in the formation process; and battery loading and unloading in the packaging process. Detailed RULA scores and corresponding risk classifications for each job position are presented in Supplementary Table S3 Table 4 RULA scores and risk levels for key job positions Work section Job position A B C D Final score Risk level Grid casting Ball milling 4 3 5 4 5 Ⅲ Continuous casting 1 1 1 1 1 Ⅰ Negative plate die casting 4 7 5 8 7 Ⅳ Plate casting 4 5 5 6 7 Ⅳ Plate processing Paste mixing 5 6 8 9 7 Ⅳ Slicing (upper plate) 4 6 7 9 7 Ⅳ Slicing (lower plate) 4 6 7 9 7 Ⅳ Coating (upper plate) 4 6 7 9 7 Ⅳ Coating (weighing) 4 4 5 5 6 Ⅲ Coating (lower plate) 4 7 7 10 7 Ⅳ Continuous coating (machine head) 3 2 3 2 3 Ⅱ Wrapping 3 2 6 5 6 Ⅲ Wrapping material collection 3 2 4 3 3 Ⅱ Assembly Manual casting and welding 3 2 3 2 3 Ⅱ Mechanical casting and welding 4 2 5 3 4 Ⅱ Glue injection 2 4 3 5 4 Ⅱ Cover sealing 3 2 6 5 6 Ⅲ Terminal welding 4 5 5 6 7 Ⅳ Component installation 4 4 5 5 6 Ⅲ Short-circuit repair 3 4 4 4 4 Ⅱ Rework 3 2 3 2 3 Ⅱ Battery hoisting 4 7 7 10 7 Ⅳ Formation Acid filling 3 2 6 5 6 Ⅲ Tank unloading 2 6 5 9 7 Ⅳ Acid extraction 2 4 3 5 4 Ⅱ Charging 4 4 5 5 6 Ⅲ Battery testing 4 4 5 5 6 Ⅲ Packaging Battery loading 4 5 7 8 7 Ⅳ Battery cleaning 2 2 3 3 3 Ⅱ Component installation 3 4 4 5 5 Ⅲ Packing 2 3 4 3 3 Ⅱ Battery unloading 4 6 7 9 7 Ⅳ Auxiliary Cleaner (seated) 1 3 1 3 3 Ⅱ Forklift operator (seated) 1 4 1 4 3 Ⅱ Forklift operator (standing) 2 2 2 2 2 Ⅰ Material handler (cart pushing/pulling) 4 3 5 4 5 Ⅲ Discussion WMSDs have been formally recognized as occupational diseases at both international and national levels, with inclusion in the International Labour Organization(ILO) List of Occupational Diseases since 2010 and the recent recognition of carpal tunnel syndrome as an occupational disease in China in 2025 14,15 . In this context, the findings of the present study provide timely evidence on the task-specific ergonomic risks contributing to WMSDs in lead-acid battery manufacturing. In the present study, the workforce in lead–acid battery manufacturing was predominantly composed of middle-aged workers with relatively low educational attainment and limited engagement in regular physical exercise. More than three-quarters of the workers had completed junior middle school education or below, a demographic profile that is characteristic of labor-intensive manufacturing industries in China. Previous epidemiological studies have shown that workers with lower educational levels are more likely to be employed in repetitive and physically demanding tasks, resulting in higher exposure to biomechanical risk factors and an increased risk of WMSDs. Similar workforce structures have been widely reported across manufacturing sectors, where low-skilled workers disproportionately occupy ergonomically high-risk positions.The predominance of middle-aged workers observed in this study may reflect workforce retention patterns in physically demanding industries, whereby younger workers exhibit higher job mobility and older workers gradually withdraw from high-load tasks due to declining physical capacity. As WMSDs are cumulative disorders, prolonged exposure to unfavorable ergonomic conditions over time substantially increases the likelihood of symptom development, which has been consistently documented in previous studies 16 , 17 . In addition, limited ergonomic awareness associated with lower educational attainment and insufficient physical exercise may further exacerbate susceptibility to musculoskeletal disorders in this occupational group. To our knowledge, this study represents the first cross-sectional investigation of WMSDs among frontline workers in lead–acid battery manufacturing in China. The findings revealed a high overall 12-month prevalence of WMSDs, with a total prevalence of 51.61% across nine body regions, indicating that more than half of the workers experienced musculoskeletal symptoms during the previous year. This prevalence is notably higher than that reported in several other key manufacturing industries in China. Jia et al. reported WMSDs prevalence rates of 40.9% in shipbuilding and related equipment manufacturing, 39.1% in electronic equipment manufacturing, and 43.6% in the automobile manufacturing industry, all of which were lower than the prevalence observed in the present study 18 .Regarding anatomical distribution, the most frequently affected body regions were the lower back, wrists/hands, shoulders, neck, and thighs/hips, with prevalence exceeding 10% in each region. Among these, the neck, shoulders, and lower back ranked as the top three affected sites. This pattern is largely consistent with findings from an epidemiological study involving more than 400 occupational groups in New Zealand, which identified the lower back, neck, and shoulders as the most commonly affected regions.(19811479) The relatively high prevalence of wrist disorders in lead–acid battery manufacturing (16.05%), second only to lower back disorders, is likely attributable to the high frequency and repetitive nature of hand-intensive tasks nufacturing (32.6%) and electronic manufacturing (10.9%) 19 .Sex-specific analysis revealed significant differences in shoulder and neck WMSDs prevalence, with female workers exhibiting substantially higher rates than male workers. This finding is consistent with previous studies conducted across multiple occupational sectors in China, which have reported a higher susceptibility to WMSDs among female workers. Differences in muscle strength, physical capacity, and tolerance to biomechanical load may partly account for this sex disparity 20 . Substantial differences in WMSDs prevalence were observed across production sections, with the highest prevalence found in packaging (63.36%), assembly (51.53%), and charging/formation (50.00%) sections. These sections represent the core production stages in lead–acid battery manufacturing and involve a large proportion of the workforce, highlighting the importance of ergonomic optimization of production processes and workstation layout to reduce musculoskeletal risk. The heatmap analysis further revealed pronounced task- and section-specific patterns of WMSDs in lead–acid battery manufacturing. Lower back disorders were consistently prevalent across nearly all production sections, indicating a shared ergonomic burden related to manual material handling, trunk flexion, and sustained standing postures. In contrast, hand/wrist disorders were particularly prominent in assembly, packaging, and auxiliary positions, reflecting intensive repetitive hand operations and forceful gripping tasks.Notably, the packaging section exhibited simultaneously elevated prevalence across multiple body regions, including the lower back, hand/wrist, neck, and shoulder, suggesting the coexistence of multiple ergonomic risk factors within this section. This multi-site risk pattern highlights packaging as a priority target for ergonomic intervention. Similar section-specific and task-dependent distributions of WMSDs have been widely reported in labor-intensive manufacturing industries, where repetitive movements, awkward postures, and manual load handling contribute to cumulative musculoskeletal burden 21 – 23 . The multivariable logistic regression analysis provided further insight into the independent determinants of site-specific WMSDs in lead–acid battery manufacturing. Adequate rest time and regular physical exercise consistently showed protective effects for both low back and wrist WMSDs, highlighting the importance of recovery capacity and physical conditioning in mitigating cumulative biomechanical load. These findings are consistent with previous occupational epidemiological studies indicating that sufficient rest and higher levels of physical activity improve musculoskeletal resilience and reduce injury risk by enhancing tissue recovery and neuromuscular function 24 .In contrast, several work-related factors significantly increased WMSDs risk. Manual handling of heavy loads and highly repetitive operations were common risk factors shared by both anatomical sites, underscoring the combined effect of forceful exertion and repetition in industrial tasks. Extensive epidemiological evidence has demonstrated that repetitive movements and manual material handling substantially increase the risk of both low back and upper-limb musculoskeletal disorders in manufacturing environments 25 , 26 .For low back WMSDs, additional risks were associated with prolonged kneeling or squatting, frequent overtime work, and exposure to cold or temperature-fluctuating environments. These findings suggest that postural constraint, extended working hours, and adverse thermal conditions may jointly contribute to lumbar disorders by increasing spinal loading, reducing muscular recovery, and impairing local circulation 27 – 29 . For wrist WMSDs, prolonged wrist flexion and sustained pinching or gripping were identified as major risk factors, reflecting the high biomechanical demands placed on the upper extremities during repetitive manual operations. Similar associations have been widely reported in studies of assembly-line and manufacturing workers, where sustained non-neutral wrist postures and forceful hand exertions were strongly linked to upper-limb disorders and carpal tunnel syndrome 1 , 30 .Interestingly, frequent smoking was associated with lower odds of wrist WMSDs in the multivariable model. This finding is more likely due to residual confounding, healthy-worker selection, or reverse causation inherent to cross-sectional analyses rather than a true protective effect. In this study, the Swedish ergonomic hazard identification method was applied for the first time to systematically assess task-level ergonomic risk in the lead–acid battery manufacturing industry. Assessment across 36 key job positions within five major production sections revealed that half of the positions exhibited ten or more adverse ergonomic factors, indicating a high overall burden of unfavorable postural and workload exposures. Hazards related to the lumbar and upper back regions were particularly prominent and were mainly associated with trunk flexion, twisting, and load handling, which is highly consistent with the questionnaire-based findings and the elevated prevalence of low back disorders observed in this study.Neck-related hazards were identified in more than half of the assessed job positions, reflecting sustained neck flexion or extension during task performance. Although the degree of neck postural demand varied across tasks, the overall exposure pattern was characterized by prolonged static loading, which aligns with the high prevalence of neck WMSDs reported in the questionnaire survey. In contrast, shoulder and upper-limb hazards were primarily related to repetitive movements and forceful exertions performed close to the trunk, rather than frequent overhead or abducted postures. This exposure profile may partly explain why the prevalence of shoulder disorders in lead–acid battery manufacturing was lower than that reported in shipbuilding and automobile manufacturing industries.Several job positions, including plate coating, sealing, slicing, mechanical casting and welding, and battery hoisting, exhibited particularly high numbers of ergonomic hazards, involving the neck, shoulders, upper back, upper limbs, and lower back simultaneously. Based on the RULA, 22 out of 36 key job positions in lead–acid battery manufacturing were classified as having medium to high ergonomic risk levels, indicating a substantial postural load across frontline operations. Positions involving frequent manual handling, repetitive bending, and sustained non-neutral postures-particularly in plate processing, pasting, assembly, and charging–formation sections—were consistently identified as high-risk. These findings are in good agreement with the questionnaire-based WMSDs prevalence results, suggesting that postural load is a major contributor to musculoskeletal disorders in this industry.For high-risk tasks such as plate splitting, pasting, and casting, workers are required to repeatedly bend, twist, and manually transport heavy materials, leading to elevated RULA scores for the trunk, neck, and upper limbs. Ergonomic interventions for these positions should prioritize training in proper manual handling techniques, correction of improper postures, and promotion of stretching exercises to reduce cumulative musculoskeletal strain. In pasting operations, providing tools with appropriate handle length may effectively reduce trunk flexion and static loading.In charging and formation processes, workers frequently adopt awkward postures due to limited workspace and variable battery heights. The use of adjustable stools, step platforms, and improved workstation layout may help minimize excessive bending and overhead arm postures. Therefore, combining RULA with the Swedish ergonomic hazard identification method provides a more comprehensive assessment of ergonomic risks.Overall, prioritizing interventions for positions with medium to high RULA risk levels—especially those involving large numbers of workers-can facilitate rapid reduction of WMSDs burden. Periodic reassessment using RULA is recommended to evaluate the effectiveness of ergonomic improvements and support continuous optimization of the working environment. Limitations This study has several limitations. First, the survey was conducted during the summer, whereas workload in the lead-acid battery industry is typically higher in autumn and winter, which may have led to underestimation of ergonomic exposure and introduced potential recall bias. Second, the cluster sampling was limited to enterprises in Jiangsu Province, which may restrict the generalizability of the findings to other regions. Third, although a validated Chinese musculoskeletal disorders questionnaire was used, some items could not be fully tailored to the specific work characteristics of lead-acid battery manufacturing, potentially limiting the specificity of exposure assessment. Abbreviations CI Confidence Interval CMQ China Musculoskeletal Questionnaire CTS Carpal Tunnel Syndrome GBD Global Burden of Disease ILO International Labour Organization NIOSH National Institute for Occupational Safety and Health OR Odds Ratio RULA Rapid Upper Limb Assessment SD Standard Deviation WHO World Health Organization WMSDs Work-related Musculoskeletal disorders YLDs Years Lived with Disability Declarations Author contributions R.Zhang, Z. Yu, and R. He contributed equally to this work (#). R.Zhang, Z. Yu, and R. He conceived and designed the study, performed data collection, and conducted the statistical analyses. D. Chen, and Q. Tang contributed to data interpretation and drafted the manuscript, with critical intellectual input and revision. L. Li and Q. Hu supported field implementation and quality control. Y. Gao oversaw the study implementation and revised the manuscript. Y. Zhao initiated and coordinated the project, secured funding, and provided overall supervision. All authors reviewed and approved the final version of the manuscript. Funding This study was supported by the Natural Science Foundation of Jiangsu Province (BK20181488), the Key Project of Jiangsu Provincial Health Commission(ZD2021024 ), the Youth General Project of Jiangsu Provincial Health Commission(MQ2024058), the Open Research Fund of Anhui Provincial Key Laboratory of Occupational Health(2024ZYJKC002),and the Program of Jiangsu Province Engineering Research Center of Health Emergency (ERCHE2022001). Availability of data and materials The datasets generated and analyzed during the current study are not publicly available due to the inclusion of potentially identifiable occupational and workplace information, but are available from the corresponding author on reasonable request. All materials used in this study (questionnaire items, ergonomic assessment forms, and analysis code) are available from the corresponding author on reasonable request. Ethics approval and consent to participate Ethics approval and consent to participate This study was conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study protocol was approved by the Ethics Committee of Jiangsu Center for Disease Control and Prevention (Approval No. JSJK2024-B013-01). Informed consent was obtained from all individual participants included in the study. Competing interests The authors declare no competing interests. References Franklin, G. M. & Friedman, A. S. Work-Related Carpal Tunnel Syndrome: Diagnosis and Treatment Guideline. Phys. Med. Rehabil. Clin. N. Am. 26 , 523–537 (2015). Zhang, H. et al. Epidemiological study of multi-site WMSDs in the footwear industry in China. Int. J. Occup. Saf. Ergon. JOSE 30 , 56–63 (2024). Cieza, A. et al. Global estimates of the need for rehabilitation based on the Global Burden of Disease study 2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet Lond. Engl. 396 , 2006–2017 (2021). Sultan-Taïeb, H. et al. Economic evaluations of ergonomic interventions preventing work-related musculoskeletal disorders: a systematic review of organizational-level interventions. BMC Public Health 17 , 935 (2017). Punnett, L. Musculoskeletal disorders and occupational exposures: how should we judge the evidence concerning the causal association? Scand. J. Public Health 42 , 49–58 (2014). 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An ergonomic intervention to relieve musculoskeletal symptoms of assembly line workers at an electronic parts manufacturer in Iran. Work Read. Mass 61 , 515–521 (2018). Dupuis, F., Cherif, A., Batcho, C., Massé-Alarie, H. & Roy, J.-S. The Tampa Scale of Kinesiophobia: A Systematic Review of Its Psychometric Properties in People With Musculoskeletal Pain. Clin. J. Pain 39 , 236–247 (2023). Zhao, H., Jia, N., Mo, S. W. & Wang, Z. X. [Research on RULA, REBA and OWAS based exposure risk assessment methods]. Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi Zhonghua Laodong Weisheng Zhiyebing Zazhi Chin. J. Ind. Hyg. Occup. Dis. 42 , 918–926 (2024). RULA: a survey method for the investigation of work-related upper limb disorders - PubMed. https://pubmed.ncbi.nlm.nih.gov/15676903/. Denisov, É. I., Mazitova, N. N., Shemetova, M. V., Chelishcheva, M. I. & Chesalin, P. V. [ILO plan of action (2010-2016) on occupational safety and health and new list of occupational diseases]. Med. Tr. Prom. Ekol. 7–13 (2011). Chen Q. Progress in the classification of work-related musculoskeletal disorders and related occupational disease lists. J. Enviromental Occup. Med. 42 , 251–253 (2025). Palmer, K. T. Occupational activities and osteoarthritis of the knee. Br. Med. Bull. 102 , 147–170 (2012). da Costa, B. R. & Vieira, E. R. Risk factors for work-related musculoskeletal disorders: A systematic review of recent longitudinal studies. Am. J. Ind. Med. 53 , 285–323 (2010). Jia, N. et al. Investigation on Work-Related Musculoskeletal Disorders - China, 2018-2019. China CDC Wkly. 2 , 299–304 (2020). Harcombe, H., McBride, D., Derrett, S. & Gray, A. Prevalence and impact of musculoskeletal disorders in New Zealand nurses, postal workers and office workers. Aust. N. Z. J. Public Health 33 , 437–441 (2009). Du, J., Zhang, L., Xu, C. & Qiao, J. Relationship Between the Exposure to Occupation-related Psychosocial and Physical Exertion and Upper Body Musculoskeletal Diseases in Hospital Nurses: A Systematic Review and Meta-analysis. Asian Nurs. Res. 15 , 163–173 (2021). Fox, R. R., Lu, M.-L., Occhipinti, E. & Jaeger, M. Understanding outcome metrics of the revised NIOSH lifting equation. Appl. Ergon. 81 , 102897 (2019). Keyserling, W. M. Workplace risk factors and occupational musculoskeletal disorders, Part 2: A review of biomechanical and psychophysical research on risk factors associated with upper extremity disorders. AIHAJ J. Sci. Occup. Environ. Health Saf. 61 , 231–243 (2000). Bezzina, A., Austin, E., Nguyen, H. & James, C. Workplace Psychosocial Factors and Their Association With Musculoskeletal Disorders: A Systematic Review of Longitudinal Studies. Workplace Health Saf. 71 , 578–588 (2023). Norheim, K. L., Samani, A., Hjort Bønløkke, J., Omland, Ø. & Madeleine, P. Physical-work ability and chronic musculoskeletal complaints are related to leisure-time physical activity: Cross-sectional study among manual workers aged 50-70 years. Scand. J. Public Health 47 , 375–382 (2019). Rotaru-Zavaleanu, A.-D. et al. Occupational Carpal Tunnel Syndrome: a scoping review of causes, mechanisms, diagnosis, and intervention strategies. Front. Public Health 12 , 1407302 (2024). Palmer, K. T., Harris, E. C. & Coggon, D. Carpal tunnel syndrome and its relation to occupation: a systematic literature review. Occup. Med. Oxf. Engl. 57 , 57–66 (2007). Ariëns, G. A., van Mechelen, W., Bongers, P. M., Bouter, L. M. & van der Wal, G. Physical risk factors for neck pain. Scand. J. Work. Environ. Health 26 , 7–19 (2000). Burdorf, A. & Sorock, G. Positive and negative evidence of risk factors for back disorders. Scand. J. Work. Environ. Health 23 , 243–256 (1997). Geneen, L. J. et al. Physical activity and exercise for chronic pain in adults: an overview of Cochrane Reviews. Cochrane Database Syst. Rev. 4 , CD011279 (2017). Epstein, S. et al. Prevalence of Work-Related Musculoskeletal Disorders Among Surgeons and Interventionalists: A Systematic Review and Meta-analysis. JAMA Surg. 153 , e174947 (2018). Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8654310","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":593447513,"identity":"19554f7b-3720-4dd5-aaf9-5094117b0deb","order_by":0,"name":"Ruoyu Zhang","email":"","orcid":"","institution":"Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Ruoyu","middleName":"","lastName":"Zhang","suffix":""},{"id":593447514,"identity":"d8763abb-9dff-42f7-987b-9d99d79ae78c","order_by":1,"name":"Zhengmin Yu","email":"","orcid":"","institution":"Jiangsu Provincial Center for Disease Control and Prevention","correspondingAuthor":false,"prefix":"","firstName":"Zhengmin","middleName":"","lastName":"Yu","suffix":""},{"id":593447515,"identity":"f78744db-2371-4b45-81c6-6aa60aae23e0","order_by":2,"name":"Renwei He","email":"","orcid":"","institution":"Suqian Center for Disease Control and Prevention","correspondingAuthor":false,"prefix":"","firstName":"Renwei","middleName":"","lastName":"He","suffix":""},{"id":593447516,"identity":"7221fb84-e94a-4acf-bc81-365ffec83497","order_by":3,"name":"Dan Chen","email":"","orcid":"","institution":"Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Dan","middleName":"","lastName":"Chen","suffix":""},{"id":593447517,"identity":"85af9bea-c4a2-47ba-b533-0574529cad3b","order_by":4,"name":"Qimeng Tang","email":"","orcid":"","institution":"Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Qimeng","middleName":"","lastName":"Tang","suffix":""},{"id":593447518,"identity":"b9621338-cf6f-4ea0-b51a-bad40769eced","order_by":5,"name":"Ling Li","email":"","orcid":"","institution":"Jiangsu Provincial Center for Disease Control and Prevention","correspondingAuthor":false,"prefix":"","firstName":"Ling","middleName":"","lastName":"Li","suffix":""},{"id":593447519,"identity":"045dca17-2d3b-41eb-bfd9-bcc6bee6fcfa","order_by":6,"name":"Qiong Hu","email":"","orcid":"","institution":"Anhui Provincial No. 2 People's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Qiong","middleName":"","lastName":"Hu","suffix":""},{"id":593447520,"identity":"40bd6db7-f127-4198-9d4a-1ea1cfcbe7a5","order_by":7,"name":"Yue Gao","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAArklEQVRIiWNgGAWjYPACG2YgYUCSljTStRxmIF6LvPvhY9I8FefZ5dsPb/zAUHOHsBbDM2lp0jxnbjMbnEkrlmA49owILQ05ZtK8bUAtEjxmDIwNh4nQ0v8GqOXfOWb5GcRqkZcA2dJwgJnhBrFaDCSeJVvOOZYM8UvCMWJs6U8+eONNjV0yOMQ+1BBjywEGFgkgnQzmJRDWALSlgYH5A5C2I0bxKBgFo2AUjFAAAGYRNU3Rs9+OAAAAAElFTkSuQmCC","orcid":"","institution":"Jiangsu Provincial Center for Disease Control and Prevention","correspondingAuthor":true,"prefix":"","firstName":"Yue","middleName":"","lastName":"Gao","suffix":""},{"id":593447521,"identity":"bcd8a2fe-b018-445b-a8a1-30307b369e46","order_by":8,"name":"Yuan Zhao","email":"","orcid":"","institution":"Jiangsu Provincial Center for Disease Control and Prevention","correspondingAuthor":false,"prefix":"","firstName":"Yuan","middleName":"","lastName":"Zhao","suffix":""}],"badges":[],"createdAt":"2026-01-21 02:38:53","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8654310/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8654310/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102986829,"identity":"229d3875-f3f4-4408-a738-892db0fd4a38","added_by":"auto","created_at":"2026-02-19 10:37:48","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":23478,"visible":true,"origin":"","legend":"\u003cp\u003ePrevalence of WMSDs by body region stratified by sex among lead-acid battery manufacturing workers.\u003c/p\u003e\n\u003cp\u003eBars represent the prevalence of WMSDs in males and females. Asterisks indicate statistically significant differences between sexes (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/fda1c27b17d16a4ff1044660.png"},{"id":102986832,"identity":"564796a0-9cc1-43ed-a089-7e93917a687f","added_by":"auto","created_at":"2026-02-19 10:37:48","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":31968,"visible":true,"origin":"","legend":"\u003cp\u003eHeatmap showing the prevalence (%) of WMSDs across body regions and production sections in lead-acid battery manufacturing.\u003c/p\u003e\n\u003cp\u003eThe color scale represents the prevalence (%) of WMSDs. Darker colors indicate higher prevalence, highlighting body regions and production sections with increased ergonomic risk.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/87e48c668aa78d7de629c339.png"},{"id":103049951,"identity":"b7ad4d45-577c-47af-bbf9-f5481d2928ea","added_by":"auto","created_at":"2026-02-20 07:47:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":122821,"visible":true,"origin":"","legend":"\u003cp\u003eForest plot of adjusted odds ratios for factors associated with low back and wrist WMSDs\u003c/p\u003e\n\u003cp\u003eForest plot illustrating adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from multivariable logistic regression analyses examining associations between individual and occupational factors and the occurrence of low back and wrist WMSDs among lead-acid battery manufacturing workers. Black squares indicate low back WMSDs, and grey circles indicate wrist WMSDs. The vertical dashed line represents the null value (OR = 1).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/cbffcba7d317bd36eedd75ee.png"},{"id":103049696,"identity":"6dc6fb3d-e638-40c5-b216-4c9714ac5654","added_by":"auto","created_at":"2026-02-20 07:44:52","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":400615,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of ergonomic hazards across body regions among key job positions.\u003c/p\u003e\n\u003cp\u003eThe body map illustrates the distribution of ergonomic hazards identified across five major body regions based on the Swedish ergonomic hazard identification checklist. Color intensity reflects the number of job positions in which ergonomic hazards were identified for each body region, with darker colors indicating a higher prevalence across job positions.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/815c764a943275f1547ac76d.png"},{"id":103056375,"identity":"1e24f01d-0acd-4e46-a534-658972afd577","added_by":"auto","created_at":"2026-02-20 09:08:27","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":9862,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of RULA risk levels among key job positions in lead-acid battery manufacturing.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/565b1081c2a2fee3f3554cc4.png"},{"id":103056718,"identity":"5fcf5394-6119-482a-8ad8-9ee154ad3bc0","added_by":"auto","created_at":"2026-02-20 09:24:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1834525,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/9bac94fc-6fae-4555-b9b9-916c0accea12.pdf"},{"id":102986830,"identity":"97d22e59-56e0-4436-a132-952a63483a29","added_by":"auto","created_at":"2026-02-19 10:37:48","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":37593,"visible":true,"origin":"","legend":"","description":"","filename":"supplementtables.docx","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/1b96e6768e54339d5e7f5972.docx"},{"id":102986834,"identity":"a556a677-fff6-45b1-b62e-763b698d3b21","added_by":"auto","created_at":"2026-02-19 10:37:48","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":454446,"visible":true,"origin":"","legend":"","description":"","filename":"JSJK2024B01301.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8654310/v1/197de776e30eff047843f28f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Ergonomic Risk Prioritization of Work-Related Musculoskeletal Disorders in Lead-Acid Battery Manufacturing: A Cross-Sectional and Observational Study","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eWork-related musculoskeletal disorders (WMSDs) constitute a major occupational health concern worldwide and represent a substantial burden in manufacturing industries. Prolonged exposure to adverse ergonomic conditions\u0026mdash;such as repetitive movements, awkward or sustained postures, and excessive physical load\u0026mdash;has been consistently identified as a key contributor to the development of WMSDs\u003csup\u003e[\u003cb\u003e1,2\u003c/b\u003e]\u003c/sup\u003e. According to the Global Burden of Disease (GBD) Study, musculoskeletal disorders affect more than 1.7\u0026nbsp;billion people globally and represent one of the leading causes of years lived with disability (YLDs), with low back pain consistently ranking as the top contributor across most age groups and regions\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. From an occupational health perspective, WMSDs account for approximately 30\u0026ndash;50% of all reported work-related health problems in industrialized countries, highlighting their dominant role among occupational diseases \u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn manufacturing settings, workers are frequently exposed to combinations of repetitive tasks, high work pace, and limited opportunities for postural variation, which promote the chronic accumulation of biomechanical load. Unlike acute occupational injuries, WMSDs typically develop insidiously and may progress from transient discomfort to persistent pain, functional limitation, and reduced work ability. These conditions are closely associated with sickness absence, decreased productivity, and premature exit from the workforce, thereby imposing substantial socioeconomic costs \u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Epidemiological evidence from manufacturing industries further supports this elevated risk. A recent systematic review and meta-analysis focusing on the automobile manufacturing industry in China reported a 12-month WMSDs prevalence of 53.1%, with the lower back, neck, and shoulders being the most frequently affected body regions. Similar prevalence patterns have been observed in other manufacturing sectors, including electronics assembly and emerging manufacturing industries, where reported WMSDs prevalence ranged from 28.6% to over 40%, depending on job type and ergonomic exposure intensity\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. These findings indicate that WMSDs remain a pervasive and unresolved occupational health issue in modern manufacturing systems.\u003c/p\u003e \u003cp\u003eHowever, existing studies on WMSDs in manufacturing industries have predominantly relied on questionnaire-based surveys to describe symptom prevalence and associated risk factors\u003csup\u003e\u003cb\u003e\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. While such approaches provide valuable epidemiological information, they often lack task-specific ergonomic assessment, thereby offering limited guidance for identifying and prioritizing high-risk operations for targeted intervention. Evidence therefore remains insufficient regarding which specific tasks contribute most to ergonomic risk in battery manufacturing environments, particularly in labor-intensive production lines.Another important methodological limitation in WMSDs research is the reliance on self-reported symptoms as a proxy for ergonomic exposure. Although symptom surveys are essential for identifying affected body regions and estimating disease prevalence, they do not necessarily reflect actual biomechanical load or postural risk. Workers performing different tasks may report similar symptoms despite markedly different ergonomic demands, highlighting the potential discrepancy between perceived discomfort and objective exposure. Consequently, there is increasing recognition of the need to integrate epidemiological approaches with observational ergonomic assessment methods.\u003c/p\u003e \u003cp\u003eStructured ergonomic hazard identification tools, such as the Swedish ergonomic risk identification method, are designed to systematically screen task-related risk factors across multiple body regions, including the neck, upper limbs, trunk, and lower extremities, by focusing on posture, repetition, force, and work organization. These checklist-based approaches allow comprehensive identification of unfavorable ergonomic conditions at the workstation and task level. In addition, the Rapid Upper Limb Assessment (RULA) method, originally developed by McAtamney and Corlett, is a widely used observational tool for evaluating postural load and physical stress affecting the neck, trunk, and upper limbs during work activities. As a systematic observational method, RULA has been extensively applied in manufacturing and assembly settings to identify high-risk tasks, quantify postural risk levels, and support ergonomic risk prioritization and intervention planning\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e,\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAgainst this background, the present study aimed to: (1) describe the prevalence and distribution of WMSDs among workers in lead-acid battery manufacturing enterprise; (2) identify task-related ergonomic hazards across key job positions using a structured ergonomic hazard identification approach; and (3) prioritize high-risk tasks based on RULA scores. By integrating epidemiological data with observational ergonomic assessment, this study seeks to provide evidence-based guidance for task-specific ergonomic interventions and to support occupational health risk management in labor-intensive manufacturing settings.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study setting and participants\u003c/h2\u003e \u003cp\u003eThe investigation was conducted in a prefecture-level city in Jiangsu Province, China, where lead\u0026ndash;acid battery manufacturing is highly concentrated. A total of 10 lead\u0026ndash;acid battery manufacturing enterprises of varying production scales were included.The field survey was carried out between May and July 2024.Several of the investigated enterprises were subsidiaries of nationally recognized lead\u0026ndash;acid battery manufacturers, featuring complete production chains and stable manufacturing capacity. Therefore, the selected enterprises were considered representative of lead\u0026ndash;acid battery manufacturing in eastern China.\u003c/p\u003e \u003cp\u003eThe study population consisted of frontline production workers employed in the selected lead\u0026ndash;acid battery manufacturing enterprises. Workers were eligible for inclusion if they met the following criteria:(1) aged 18 years or older; (2) had at least one year of work experience in lead\u0026ndash;acid battery manufacturing.Workers were excluded if they were pregnant, had physical disabilities, or reported musculoskeletal disorders caused by non-occupational factors, such as acute trauma or chronic metabolic diseases.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Sample size determination\u003c/h2\u003e \u003cp\u003eThe required sample size was estimated using standard methods for cross-sectional studies. In the absence of prior prevalence data on WMSDs among lead-acid battery manufacturing workers, the expected prevalence was conservatively set at 0.50. With a 95% confidence level and an absolute precision of 2.19%, the minimum sample size was estimated at approximately 2,203 participants. To account for potential non-response, the target sample size was increased by 10%. To ensure representativeness, at least 30% of frontline workers from each enterprise were surveyed.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Questionnaire Survey\u003c/h2\u003e \u003cp\u003e The epidemiological cross-sectional survey was conducted using the electronic version of the Chinese Musculoskeletal Disorders Questionnaire(CMQ) provided by the Occupational Health and Poison Control Institute of the Chinese Center for Disease Control and Prevention. This questionnaire has demonstrated good reliability and validity. Participants completed the questionnaire on site in small groups, with trained investigators providing standardized instructions.The questionnaire consisted of three sections. The first section collected basic demographic and personal information, including sex, age, height, weight, job type, years of service, educational level, and medical history. The second section addressed musculoskeletal symptoms, covering nine body regions\u0026mdash;neck, shoulder, upper back, lower back (lumbar), elbow, wrist/hand, hip/leg, knee, and ankle/foot\u0026mdash;and recorded the occurrence, duration, and frequency of pain or discomfort over the past 12 months. The third section focused on work-related factors, including work type, organization of tasks, break schedules, and working postures. Participants accessed the questionnaire by scanning a QR code, and responses were submitted electronically, directly uploading data to an online database for analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Evaluation of Work-Related Musculoskeletal Disorders\u003c/h2\u003e \u003cp\u003e WMSDs in this study were evaluated following the guidelines of the National Institute for Occupational Safety and Health (NIOSH). WMSDs were considered present if participants reported discomfort-including pain, stiffness, burning, numbness, or tingling-while fulfilling all of the following conditions: (1) symptoms occurred within the previous 12 months; (2) symptoms started after beginning the current job; (3) the affected area was not influenced by prior accidents or acute injuries; and (4) symptoms occurred at least once per month or persisted for more than one week in total. The prevalence of WMSDs in a specific body region was calculated as the number of affected individuals divided by the total number of participants, whereas overall WMSDs prevalence was defined as the proportion of participants reporting symptoms in any body region.\u003c/p\u003e \u003cp\u003eThis study adopted a cross-sectional observational ergonomic assessment design to investigate WMSDs risks in lead\u0026ndash;acid battery manufacturing. Field investigations were conducted in 10 lead\u0026ndash;acid battery manufacturing enterprises located in Jiangsu Province, China. These enterprises varied in production scale, level of automation, and organizational management, but shared comparable core manufacturing processes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Video Recording of Key Work Tasks\u003c/h2\u003e \u003cp\u003eDuring the on-site investigation, trained investigators accompanied the enterprise safety officers to various production workshops to conduct video recordings of key work tasks and job categories. Mobile phones or tablet devices were used to record workers\u0026rsquo; task performance without interfering with their normal work activities. For each workstation or job type, video recordings captured the workers from the left side, right side, and front view. At least three work cycles were observed per workstation, with each video lasting approximately 2\u0026ndash;5 min.Additionally, for each job type, task performance was recorded for a minimum of three different workers to ensure representativeness.\u003c/p\u003e \u003cp\u003eTo optimize data collection efficiency and minimize disruption to routine production activities, video recording was conducted concurrently with the questionnaire survey. Dedicated team members were responsible for video acquisition throughout the field investigation. All video recordings were collected between May and July 2024.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Swedish ergonomic hazard identification\u003c/h2\u003e \u003cp\u003eErgonomic risk factors were assessed using the Swedish ergonomic hazard identification checklist. The validated Chinese version was used to screen potentially hazardous body regions and related ergonomic risk factors during work tasks. The checklist covers five body regions: (1) neck, shoulders, and upper back; (2) elbows, forearms, and wrists; (3) feet; (4) knees and thighs/hips; and (5) lower back, comprising 17 items in total.\u003c/p\u003e \u003cp\u003eVideo recordings of each workstation/task were reviewed repeatedly and coded against the 17 checklist items. The assessment followed a standardized procedure: (1) reviewing videos to identify body regions potentially at risk; (2) mapping the identified regions to relevant checklist items to determine specific hazards; (3) marking applicable items on the checklist; and (4) recording additional contextual factors that may increase musculoskeletal strain, including limited ability to pause work, low task/workspace autonomy, time pressure or psychosocial stress, abnormal/unexpected work conditions, adverse environmental exposures (e.g., cold/heat/noise), and rapid movements, shaking, or vibration. Where discrepancies occurred, assessors discussed the recordings and reached consensus.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Ergonomic risk assessment using RULA\u003c/h2\u003e \u003cp\u003eThe Rapid Upper Limb Assessment (RULA) method was used to evaluate the level of ergonomic risk associated with each key task. The validated Chinese version of RULA was applied.RULA divides the body into two groups(Group A: upper arm, lower arm, and wrist;Group B: neck, trunk, and legs).Postural scores were determined based on observed working postures, and additional scores were assigned according to muscle use and external load. Final RULA scores range from 1 to 7, corresponding to four action levels:Level 1 (scores 1\u0026ndash;2): acceptable risk;Level 2 (scores 3\u0026ndash;4): further investigation required;Level 3 (scores 5\u0026ndash;6): investigation and changes needed soon;Level 4 (score 7): investigation and changes required immediately.To account for inter-individual variability, three workers per task were independently evaluated. Two trained researchers conducted RULA assessments independently, and the mean score rounded to the nearest integer was used as the final RULA score for each task.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.8 Quality control\u003c/h2\u003e \u003cp\u003eAll investigators received standardized training prior to data collection. During the survey, unified instructions were provided, and questionnaires were completed independently by participants under on-site supervision.Questionnaires were checked on site for completeness and logical consistency.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e2.9 Statistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using IBM SPSS Statistics version 23.0 (network licensed edition).Continuous variables were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, and categorical variables as frequencies and percentages. The 12-month prevalence of work-related musculoskeletal disorders (WMSDs) was calculated overall and stratified by sex, body region, and production section.Group differences in WMSDs prevalence were assessed using the chi-square (χ\u0026sup2;) test. Multivariable logistic regression analyses were conducted to identify factors associated with low back and wrist WMSDs. Ergonomic hazards identified using the Swedish ergonomic hazard identification method and RULA scores were summarized descriptively. All tests were two-sided, and \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Demographic and occupational characteristics\u003c/h2\u003e \u003cp\u003eA total of 2,609 frontline workers from 10 lead\u0026ndash;acid battery manufacturing enterprises in Jiangsu Province were initially surveyed. In each enterprise, the number of participants accounted for more than 30% of the frontline workforce. After excluding 191 invalid questionnaires, 2,418 valid questionnaires were included in the final analysis, yielding a response rate of 92.68%. The final sample size exceeded the estimated minimum requirement and was considered sufficient for statistical analysis.\u003c/p\u003e \u003cp\u003eAmong the included participants, 1,335 were male and 1,083 were female. The mean age of the workers was 41.55\u0026thinsp;\u0026plusmn;\u0026thinsp;7.65 years, and the mean duration of employment was 4.45\u0026thinsp;\u0026plusmn;\u0026thinsp;3.74 years. For male workers, the mean height was 171.45\u0026thinsp;\u0026plusmn;\u0026thinsp;6.27 cm, mean body weight was 70.83\u0026thinsp;\u0026plusmn;\u0026thinsp;11.21 kg, and mean body mass index (BMI) was 24.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.50 kg/m\u0026sup2;. Female workers had a mean height of 159.85\u0026thinsp;\u0026plusmn;\u0026thinsp;5.80 cm, mean body weight of 59.61\u0026thinsp;\u0026plusmn;\u0026thinsp;9.58 kg, and mean BMI of 23.32\u0026thinsp;\u0026plusmn;\u0026thinsp;3.56 kg/m\u0026sup2;.\u003c/p\u003e \u003cp\u003eRegarding educational attainment, 78.33% of the participants had completed junior middle school or below, 18.03% had senior high school or vocational education, and 3.64% had attained college level or higher education. With respect to physical exercise habits, 56.74% of the workers reported no regular physical exercise, 32.71% reported occasional exercise, and 10.55% reported regular physical exercise(Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic characteristics of lead-acid battery manufacturing workers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDemographic characteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN(%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e561(23.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e334(13.81)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e227(9.39)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e35\u0026thinsp;~\u0026thinsp;44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1156(47.81)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e597(24.69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e559(23.12)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e701(28.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e404(16.71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e297(12.28)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI(kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;18.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74(3.06)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32(1.32)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42(1.74)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18.5\u0026thinsp;~\u0026thinsp;23.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1300(53.76)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e650(26.88)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e650(26.88)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e24.0\u0026thinsp;~\u0026thinsp;27.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e831(34.37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e511(21.13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e320(13.23)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;28.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e213(8.81)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e142(5.87)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e71(2.94)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYears of employment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u0026thinsp;~\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1512(62.53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e842(34.82)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e670(27.71)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u0026thinsp;~\u0026thinsp;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e581(24.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e307(12.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e274(11.33)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e325(13.44)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e186(7.69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e139(5.75)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDominant hand\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeft\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e136(5.62)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e92(3.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44(1.82)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2282(94.38)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1243(51.41)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1039(42.97)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEducation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eJunior middle school or below\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1894(78.33)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e941(38.92)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e953(39.41)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSenior high school or vocational school\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e436(18.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e326(13.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e110(4.55)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCollege or above\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e88(3.64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e68(2.81)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20(0.83)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMarital status\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnmarried\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43(1.78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29(1.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14(0.58)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emarried\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2338(96.69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1281(52.98)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1057(43.71)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther (divorced or widowed)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37(1.53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25(1.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12(0.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMonthly income (RMB)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;3000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31(1.28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9(0.37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22(0.91)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3000\u0026thinsp;~\u0026thinsp;5000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e309(12.78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e150(6.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e159(6.58)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;5000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2078(85.94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1176(48.64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e902(37.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Prevalence and anatomical distribution of WMSDs\u003c/h2\u003e \u003cp\u003eA total of 2,418 frontline workers from lead-acid battery manufacturing enterprises were included in the analysis. The overall 12-month prevalence of work-related musculoskeletal disorders (WMSDs) was 51.61%.The most frequently affected body regions were the lower back, hand/wrist, shoulder, neck, and thigh/hip (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Among these regions, lower back symptoms showed the highest prevalence. Female workers reported a notably higher prevalence of neck and shoulder symptoms compared with male workers, whereas no substantial sex differences were observed for lower back or hand/wrist disorders.These findings indicate that WMSDs are highly prevalent in lead-acid battery manufacturing, with symptoms predominantly concentrated in the trunk and upper extremities(Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePrevalence of WMSDs by Body Region among Lead-Acid Battery Manufacturing Workers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eBody region\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eχ\u0026sup2;\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN(%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1248(51.61)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e656(49.14)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e592(54.66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLower back\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e471(19.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e264(10.92)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e207(8.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWrist/Hand\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e392(16.21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e201(8.31)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e191(7.90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eShoulder\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e315(13.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e128(5.29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e187(7.73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e31.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeck\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e283(11.70)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e91(3.76)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e192(17.73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e68.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThigh/Hip\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e274(11.33)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e141(10.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e133(12.28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElbow\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e135(5.58)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e76(3.14)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e59(2.44)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle/Foot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e120(4.96)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e60(2.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e60(2.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e78(3.23)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e40(1.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e38(1.57)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUpper back\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e60(2.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e27(1.12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e33(1.36)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eP\u003c/em\u003e values were calculated using the chi-square test.\u003c/p\u003e \u003cp\u003ePercentages in the Overall column were calculated using the total sample size (N\u0026thinsp;=\u0026thinsp;2418) as the denominator; percentages in the Male and Female columns were calculated using the male (N\u0026thinsp;=\u0026thinsp;1335) and female (N\u0026thinsp;=\u0026thinsp;1083) subgroups as denominators, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBars represent the prevalence of WMSDs in males and females. Asterisks indicate statistically significant differences between sexes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Prevalence of WMSDs across Different Production Sections in Lead-acid Battery Manufacturing\u003c/h2\u003e \u003cp\u003eThe prevalence of WMSDs varied across production sections in the lead-acid battery manufacturing process (section-specific analyses included 2,393 workers; 25 workers with mixed duties across sections were not included in this stratified analysis). Among all sections, the highest prevalence was observed in packaging (63.36%), followed by assembly (51.53%) and charging/formation (50.00%).Regarding specific body regions, the top three affected areas in the grid casting section were the lower back, shoulders, and thighs/buttocks; in the plate processing section, they were the lower back, hands/wrists, and thighs/buttocks; in the assembly and charging/formation sections, the most affected regions were the hands/wrists, lower back, and shoulders; in the packaging section, the lower back, hands/wrists, and neck were most frequently affected. Statistically significant differences in WMSDs prevalence among sections were observed for the lower back, hands/wrists, neck, and thighs/buttocks (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePrevalence of WMSDs by Body Region in Different Production Sections\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProduction Section\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal WMSDs\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNeck\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eShoulder\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUpper Back\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eLower Back\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eElbow\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eHand/\u003c/p\u003e \u003cp\u003eWrist\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eThigh/\u003c/p\u003e \u003cp\u003eButtock\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eKnee\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eAnkle/Foot\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrid Casting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e273\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e107(39.19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e19(6.96)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27(9.89)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4(1.47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e45(16.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e11(4.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e12(4.40)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e23(8.42)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e6(2.20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e19(6.96)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePlate Processing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e482\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e239(49.59)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e49(10.17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e58(12.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6(1.24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e100(20.76)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e22(4.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e72(14.94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e55(11.41)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e14(2.90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e19(3.94)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAssembly\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e925\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e476(51.53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e107(10.94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e116(11.27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e26(2.74)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e166(16.08)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e57(6.13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e172(17.83)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e98(10.72)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e31(3.17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e38(3.83)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharging/\u003c/p\u003e \u003cp\u003eFormation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e497\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e249(50.00)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e70(13.25)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e70(14.66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e13(2.61)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e99(18.27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e23(4.22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e79(15.66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e53(10.24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e18(3.21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e26(5.02)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePackaging\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e199\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e127(63.32)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e36(18.09)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e34(16.08)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e10(5.53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e56(27.64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e18(8.04)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e46(24.21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e35(18.59)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e7(3.52)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e14(6.53)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOthers\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e25(60.47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2(4.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10(23.26)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1(2.33)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e5(11.63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4(9.30)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e11(27.91)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e6(13.95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e2(4.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e4(9.30)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2418\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1223(50.58)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e283(11.70)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e315(13.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e60(2.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e471(19.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e135(5.58)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e392(16.21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e274(11.33)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e78(3.23)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e120(4.96)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eχ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e29.979\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e19.604\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.678\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9.986\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14.558\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e9.410\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e42.601\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e11.214\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e1.752\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e8.546\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.058\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.076\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.094\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e0.047\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.882\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.129\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe color scale represents the prevalence (%) of WMSDs. Darker colors indicate higher prevalence, highlighting body regions and production sections with increased ergonomic risk.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Multivariable Logistic Regression Analysis of Low Back and Wrist WMSDs\u003c/h2\u003e \u003cp\u003eMultivariable logistic regression was used to identify factors associated with low back and wrist WMSDs. For low back WMSDs, adequate rest time (OR\u0026thinsp;=\u0026thinsp;0.472, 95% CI: 0.363\u0026ndash;0.615) and physical exercise (regular: OR\u0026thinsp;=\u0026thinsp;0.579, 95% CI: 0.370\u0026ndash;0.906; occasional: OR\u0026thinsp;=\u0026thinsp;0.642, 95% CI: 0.495\u0026ndash;0.833) were protective. Increased odds were observed for occasional smoking (OR\u0026thinsp;=\u0026thinsp;1.727, 95% CI: 1.147\u0026ndash;2.603), fair self-rated health (OR\u0026thinsp;=\u0026thinsp;2.108, 95% CI: 1.624\u0026ndash;2.737), manual handling of loads\u0026thinsp;\u0026gt;\u0026thinsp;5 kg per lift (OR\u0026thinsp;=\u0026thinsp;1.828, 95% CI: 1.374\u0026ndash;2.432), highly repetitive operations (OR\u0026thinsp;=\u0026thinsp;1.411, 95% CI: 1.076\u0026ndash;1.851), frequent overtime (OR\u0026thinsp;=\u0026thinsp;1.350, 95% CI: 1.055\u0026ndash;1.727), and cold/temperature-fluctuating environments (OR\u0026thinsp;=\u0026thinsp;1.560, 95% CI: 1.042\u0026ndash;2.335). Poor self-rated health (OR\u0026thinsp;=\u0026thinsp;2.222, 95% CI: 0.579\u0026ndash;8.521) and prolonged kneeling/squatting (OR\u0026thinsp;=\u0026thinsp;1.957, 95% CI: 0.966\u0026ndash;3.966) showed positive but non-significant associations.\u003c/p\u003e \u003cp\u003eFor wrist WMSDs, employment duration\u0026thinsp;\u0026ge;\u0026thinsp;10 years (OR\u0026thinsp;=\u0026thinsp;0.529, 95% CI: 0.349\u0026ndash;0.801), regular exercise (OR\u0026thinsp;=\u0026thinsp;0.577, 95% CI: 0.344\u0026ndash;0.966), frequent smoking (OR\u0026thinsp;=\u0026thinsp;0.485, 95% CI: 0.356\u0026ndash;0.662), and adequate rest time (OR\u0026thinsp;=\u0026thinsp;0.590, 95% CI: 0.445\u0026ndash;0.784) were protective, whereas prolonged wrist flexion (OR\u0026thinsp;=\u0026thinsp;1.417, 95% CI: 1.092\u0026ndash;1.839), heavy loads\u0026thinsp;\u0026gt;\u0026thinsp;5 kg (OR\u0026thinsp;=\u0026thinsp;1.538, 95% CI: 1.136\u0026ndash;2.081), very heavy loads\u0026thinsp;\u0026gt;\u0026thinsp;20 kg (OR\u0026thinsp;=\u0026thinsp;1.509, 95% CI: 1.135\u0026ndash;2.006), and sustained pinching/gripping (OR\u0026thinsp;=\u0026thinsp;1.860, 95% CI: 1.253\u0026ndash;2.760) increased the odds. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e summarizes the site-specific patterns; full outputs are provided in Supplementary Tables S1\u0026ndash;S2.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eForest plot illustrating adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from multivariable logistic regression analyses examining associations between individual and occupational factors and the occurrence of low back and wrist WMSDs among lead-acid battery manufacturing workers. Black squares indicate low back WMSDs, and grey circles indicate wrist WMSDs. The vertical dashed line represents the null value (OR\u0026thinsp;=\u0026thinsp;1).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Identification Results of Hazardous Factors in Key Work Positions\u003c/h2\u003e \u003cp\u003eBased on the checklist items of the Swedish ergonomic hazard identification method, hazards were assessed across five body regions in 36 job positions. Adverse ergonomic factors were identified to varying degrees in all five body regions across the 36 job positions. Specifically, the neck, shoulders, and upper back were affected in 34 job positions; the elbows, forearms, and wrists were involved in 29 job positions. For the lower limbs, 14 job positions exhibited adverse factors in the feet, while 15 job positions showed issues in the knees and hips, primarily related to \u0026ldquo;working in a standing posture without sitting or support\u0026rdquo; or \u0026ldquo;restricted workspace or limited material handling.\u0026rdquo; Additionally, the lumbar region was affected in 28 job positions. Details are provided in Supplement Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The distribution of ergonomic hazards across tasks and body regions is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe body map illustrates the distribution of ergonomic hazards identified across five major body regions based on the Swedish ergonomic hazard identification checklist. Color intensity reflects the number of job positions in which ergonomic hazards were identified for each body region, with darker colors indicating a higher prevalence across job positions.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e3.6 RULA-based risk levels and task prioritization\u003c/h2\u003e \u003cp\u003eRULA scores for the 36 job positions in lead-acid battery manufacturing ranged from 1 to 7, corresponding to risk Levels I to IV. Among these positions, 2 job positions (5.56%) were classified as Level I, 12 positions (33.33%) as Level II, 10 positions (27.78%) as Level III, and 12 positions (33.33%) as Level IV.\u003c/p\u003e \u003cp\u003e According to RULA guidelines, both Level III and Level IV indicate the need for ergonomic interventions. Level III represents job positions where further investigation and corrective actions are required, including ball milling in the grid casting process; coating (weighing) and wrapping in the plate processing process; cover sealing and component installation in the assembly process; acid filling, charging, and battery testing in the formation process; component installation in the packaging process; as well as auxiliary positions such as material handling (cart pushing and pulling).\u003c/p\u003e \u003cp\u003eLevel IV indicates job positions requiring urgent ergonomic interventions. These positions mainly included negative plate die casting and plate casting in the grid casting process; paste mixing, slicing (upper and lower plate), and coating (lower plate) in the plate processing process; terminal welding and battery hoisting in the assembly process; tank unloading in the formation process; and battery loading and unloading in the packaging process.\u003c/p\u003e \u003cp\u003eDetailed RULA scores and corresponding risk classifications for each job position are presented in Supplementary Table S3\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRULA scores and risk levels for key job positions\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWork section\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eJob position\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFinal score\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eRisk level\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrid casting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBall milling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eContinuous casting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅠ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNegative plate die casting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePlate casting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePlate processing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePaste mixing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSlicing (upper plate)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSlicing (lower plate)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCoating (upper plate)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCoating (weighing)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCoating (lower plate)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eContinuous coating (machine head)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWrapping\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWrapping material collection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAssembly\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eManual casting and welding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMechanical casting and welding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGlue injection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCover sealing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTerminal welding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eComponent installation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eShort-circuit repair\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRework\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBattery hoisting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFormation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAcid filling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTank unloading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAcid extraction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCharging\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBattery testing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePackaging\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBattery loading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBattery cleaning\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eComponent installation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePacking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBattery unloading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAuxiliary\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCleaner (seated)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eForklift operator (seated)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eForklift operator (standing)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅠ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMaterial handler (cart pushing/pulling)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eWMSDs have been formally recognized as occupational diseases at both international and national levels, with inclusion in the International Labour Organization(ILO) List of Occupational Diseases since 2010 and the recent recognition of carpal tunnel syndrome as an occupational disease in China in 2025\u003csup\u003e14,15\u003c/sup\u003e. In this context, the findings of the present study provide timely evidence on the task-specific ergonomic risks contributing to WMSDs in lead-acid battery manufacturing.\u003c/p\u003e \u003cp\u003eIn the present study, the workforce in lead\u0026ndash;acid battery manufacturing was predominantly composed of middle-aged workers with relatively low educational attainment and limited engagement in regular physical exercise. More than three-quarters of the workers had completed junior middle school education or below, a demographic profile that is characteristic of labor-intensive manufacturing industries in China. Previous epidemiological studies have shown that workers with lower educational levels are more likely to be employed in repetitive and physically demanding tasks, resulting in higher exposure to biomechanical risk factors and an increased risk of WMSDs. Similar workforce structures have been widely reported across manufacturing sectors, where low-skilled workers disproportionately occupy ergonomically high-risk positions.The predominance of middle-aged workers observed in this study may reflect workforce retention patterns in physically demanding industries, whereby younger workers exhibit higher job mobility and older workers gradually withdraw from high-load tasks due to declining physical capacity. As WMSDs are cumulative disorders, prolonged exposure to unfavorable ergonomic conditions over time substantially increases the likelihood of symptom development, which has been consistently documented in previous studies \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. In addition, limited ergonomic awareness associated with lower educational attainment and insufficient physical exercise may further exacerbate susceptibility to musculoskeletal disorders in this occupational group.\u003c/p\u003e \u003cp\u003eTo our knowledge, this study represents the first cross-sectional investigation of WMSDs among frontline workers in lead\u0026ndash;acid battery manufacturing in China. The findings revealed a high overall 12-month prevalence of WMSDs, with a total prevalence of 51.61% across nine body regions, indicating that more than half of the workers experienced musculoskeletal symptoms during the previous year. This prevalence is notably higher than that reported in several other key manufacturing industries in China. Jia et al. reported WMSDs prevalence rates of 40.9% in shipbuilding and related equipment manufacturing, 39.1% in electronic equipment manufacturing, and 43.6% in the automobile manufacturing industry, all of which were lower than the prevalence observed in the present study\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e.Regarding anatomical distribution, the most frequently affected body regions were the lower back, wrists/hands, shoulders, neck, and thighs/hips, with prevalence exceeding 10% in each region. Among these, the neck, shoulders, and lower back ranked as the top three affected sites. This pattern is largely consistent with findings from an epidemiological study involving more than 400 occupational groups in New Zealand, which identified the lower back, neck, and shoulders as the most commonly affected regions.(19811479) The relatively high prevalence of wrist disorders in lead\u0026ndash;acid battery manufacturing (16.05%), second only to lower back disorders, is likely attributable to the high frequency and repetitive nature of hand-intensive tasks nufacturing (32.6%) and electronic manufacturing (10.9%)\u003csup\u003e19\u003c/sup\u003e.Sex-specific analysis revealed significant differences in shoulder and neck WMSDs prevalence, with female workers exhibiting substantially higher rates than male workers. This finding is consistent with previous studies conducted across multiple occupational sectors in China, which have reported a higher susceptibility to WMSDs among female workers. Differences in muscle strength, physical capacity, and tolerance to biomechanical load may partly account for this sex disparity\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSubstantial differences in WMSDs prevalence were observed across production sections, with the highest prevalence found in packaging (63.36%), assembly (51.53%), and charging/formation (50.00%) sections. These sections represent the core production stages in lead\u0026ndash;acid battery manufacturing and involve a large proportion of the workforce, highlighting the importance of ergonomic optimization of production processes and workstation layout to reduce musculoskeletal risk. The heatmap analysis further revealed pronounced task- and section-specific patterns of WMSDs in lead\u0026ndash;acid battery manufacturing. Lower back disorders were consistently prevalent across nearly all production sections, indicating a shared ergonomic burden related to manual material handling, trunk flexion, and sustained standing postures. In contrast, hand/wrist disorders were particularly prominent in assembly, packaging, and auxiliary positions, reflecting intensive repetitive hand operations and forceful gripping tasks.Notably, the packaging section exhibited simultaneously elevated prevalence across multiple body regions, including the lower back, hand/wrist, neck, and shoulder, suggesting the coexistence of multiple ergonomic risk factors within this section. This multi-site risk pattern highlights packaging as a priority target for ergonomic intervention. Similar section-specific and task-dependent distributions of WMSDs have been widely reported in labor-intensive manufacturing industries, where repetitive movements, awkward postures, and manual load handling contribute to cumulative musculoskeletal burden \u003csup\u003e\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe multivariable logistic regression analysis provided further insight into the independent determinants of site-specific WMSDs in lead\u0026ndash;acid battery manufacturing. Adequate rest time and regular physical exercise consistently showed protective effects for both low back and wrist WMSDs, highlighting the importance of recovery capacity and physical conditioning in mitigating cumulative biomechanical load. These findings are consistent with previous occupational epidemiological studies indicating that sufficient rest and higher levels of physical activity improve musculoskeletal resilience and reduce injury risk by enhancing tissue recovery and neuromuscular function \u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e.In contrast, several work-related factors significantly increased WMSDs risk. Manual handling of heavy loads and highly repetitive operations were common risk factors shared by both anatomical sites, underscoring the combined effect of forceful exertion and repetition in industrial tasks. Extensive epidemiological evidence has demonstrated that repetitive movements and manual material handling substantially increase the risk of both low back and upper-limb musculoskeletal disorders in manufacturing environments\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e.For low back WMSDs, additional risks were associated with prolonged kneeling or squatting, frequent overtime work, and exposure to cold or temperature-fluctuating environments. These findings suggest that postural constraint, extended working hours, and adverse thermal conditions may jointly contribute to lumbar disorders by increasing spinal loading, reducing muscular recovery, and impairing local circulation\u003csup\u003e\u003cspan additionalcitationids=\"CR28\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. For wrist WMSDs, prolonged wrist flexion and sustained pinching or gripping were identified as major risk factors, reflecting the high biomechanical demands placed on the upper extremities during repetitive manual operations. Similar associations have been widely reported in studies of assembly-line and manufacturing workers, where sustained non-neutral wrist postures and forceful hand exertions were strongly linked to upper-limb disorders and carpal tunnel syndrome\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e.Interestingly, frequent smoking was associated with lower odds of wrist WMSDs in the multivariable model. This finding is more likely due to residual confounding, healthy-worker selection, or reverse causation inherent to cross-sectional analyses rather than a true protective effect.\u003c/p\u003e \u003cp\u003eIn this study, the Swedish ergonomic hazard identification method was applied for the first time to systematically assess task-level ergonomic risk in the lead\u0026ndash;acid battery manufacturing industry. Assessment across 36 key job positions within five major production sections revealed that half of the positions exhibited ten or more adverse ergonomic factors, indicating a high overall burden of unfavorable postural and workload exposures. Hazards related to the lumbar and upper back regions were particularly prominent and were mainly associated with trunk flexion, twisting, and load handling, which is highly consistent with the questionnaire-based findings and the elevated prevalence of low back disorders observed in this study.Neck-related hazards were identified in more than half of the assessed job positions, reflecting sustained neck flexion or extension during task performance. Although the degree of neck postural demand varied across tasks, the overall exposure pattern was characterized by prolonged static loading, which aligns with the high prevalence of neck WMSDs reported in the questionnaire survey. In contrast, shoulder and upper-limb hazards were primarily related to repetitive movements and forceful exertions performed close to the trunk, rather than frequent overhead or abducted postures. This exposure profile may partly explain why the prevalence of shoulder disorders in lead\u0026ndash;acid battery manufacturing was lower than that reported in shipbuilding and automobile manufacturing industries.Several job positions, including plate coating, sealing, slicing, mechanical casting and welding, and battery hoisting, exhibited particularly high numbers of ergonomic hazards, involving the neck, shoulders, upper back, upper limbs, and lower back simultaneously.\u003c/p\u003e \u003cp\u003eBased on the RULA, 22 out of 36 key job positions in lead\u0026ndash;acid battery manufacturing were classified as having medium to high ergonomic risk levels, indicating a substantial postural load across frontline operations. Positions involving frequent manual handling, repetitive bending, and sustained non-neutral postures-particularly in plate processing, pasting, assembly, and charging\u0026ndash;formation sections\u0026mdash;were consistently identified as high-risk. These findings are in good agreement with the questionnaire-based WMSDs prevalence results, suggesting that postural load is a major contributor to musculoskeletal disorders in this industry.For high-risk tasks such as plate splitting, pasting, and casting, workers are required to repeatedly bend, twist, and manually transport heavy materials, leading to elevated RULA scores for the trunk, neck, and upper limbs. Ergonomic interventions for these positions should prioritize training in proper manual handling techniques, correction of improper postures, and promotion of stretching exercises to reduce cumulative musculoskeletal strain. In pasting operations, providing tools with appropriate handle length may effectively reduce trunk flexion and static loading.In charging and formation processes, workers frequently adopt awkward postures due to limited workspace and variable battery heights. The use of adjustable stools, step platforms, and improved workstation layout may help minimize excessive bending and overhead arm postures. Therefore, combining RULA with the Swedish ergonomic hazard identification method provides a more comprehensive assessment of ergonomic risks.Overall, prioritizing interventions for positions with medium to high RULA risk levels\u0026mdash;especially those involving large numbers of workers-can facilitate rapid reduction of WMSDs burden. Periodic reassessment using RULA is recommended to evaluate the effectiveness of ergonomic improvements and support continuous optimization of the working environment.\u003c/p\u003e \u003cp\u003e \u003cb\u003eLimitations\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThis study has several limitations. First, the survey was conducted during the summer, whereas workload in the lead-acid battery industry is typically higher in autumn and winter, which may have led to underestimation of ergonomic exposure and introduced potential recall bias. Second, the cluster sampling was limited to enterprises in Jiangsu Province, which may restrict the generalizability of the findings to other regions. Third, although a validated Chinese musculoskeletal disorders questionnaire was used, some items could not be fully tailored to the specific work characteristics of lead-acid battery manufacturing, potentially limiting the specificity of exposure assessment.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eConfidence Interval\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCMQ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eChina Musculoskeletal Questionnaire\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCTS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCarpal Tunnel Syndrome\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGBD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGlobal Burden of Disease\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eILO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eInternational Labour Organization\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNIOSH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNational Institute for Occupational Safety and Health\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eOR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eOdds Ratio\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eRULA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eRapid Upper Limb Assessment\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eStandard Deviation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWHO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWorld Health Organization\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWMSDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWork-related Musculoskeletal disorders\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYLDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYears Lived with Disability\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eR.Zhang, Z. Yu, and R. He contributed equally to this work (#). R.Zhang, Z. Yu, and R. He conceived and designed the study, performed data collection, and conducted the statistical analyses. D. Chen, and Q. Tang contributed to data interpretation and drafted the manuscript, with critical intellectual input and revision. L. Li and Q. Hu supported field implementation and quality control. Y. Gao oversaw the study implementation and revised the manuscript. Y. Zhao initiated and coordinated the project, secured funding, and provided overall supervision. All authors reviewed and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Natural Science Foundation of Jiangsu Province (BK20181488), the Key Project of Jiangsu Provincial Health Commission(ZD2021024 ), the Youth General Project of Jiangsu Provincial Health Commission(MQ2024058), the Open Research Fund of Anhui Provincial Key Laboratory of Occupational Health(2024ZYJKC002),and the Program of Jiangsu Province Engineering Research Center of Health Emergency (ERCHE2022001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are not publicly available due to the inclusion of potentially identifiable occupational and workplace information, but are available from the corresponding author on reasonable request. All materials used in this study (questionnaire items, ergonomic assessment forms, and analysis code) are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthics approval and consent to participate This study was conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study protocol was approved by the Ethics Committee of Jiangsu Center for Disease Control and Prevention (Approval No. JSJK2024-B013-01). Informed consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eFranklin, G. M. \u0026amp; Friedman, A. S. Work-Related Carpal Tunnel Syndrome: Diagnosis and Treatment Guideline. \u003cem\u003ePhys. Med. Rehabil. Clin. N. Am.\u003c/em\u003e \u003cstrong\u003e26\u003c/strong\u003e, 523\u0026ndash;537 (2015).\u003c/li\u003e\n\u003cli\u003eZhang, H. \u003cem\u003eet al.\u003c/em\u003e Epidemiological study of multi-site WMSDs in the footwear industry in China. \u003cem\u003eInt. J. Occup. Saf. Ergon. 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Rev.\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, CD011279 (2017).\u003c/li\u003e\n\u003cli\u003eEpstein, S. \u003cem\u003eet al.\u003c/em\u003e Prevalence of Work-Related Musculoskeletal Disorders Among Surgeons and Interventionalists: A Systematic Review and Meta-analysis. \u003cem\u003eJAMA Surg.\u003c/em\u003e \u003cstrong\u003e153\u003c/strong\u003e, e174947 (2018).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pubh","sideBox":"Learn more about [BMC Public Health](http://bmcpublichealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pubh/default.aspx","title":"BMC Public Health","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"work-related musculoskeletal disorders, lead–acid battery manufacturing, ergonomic risk factors, Rapid Upper Limb Assessment, Swedish ergonomic hazard identification method, occupational health","lastPublishedDoi":"10.21203/rs.3.rs-8654310/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8654310/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjectives\u003c/strong\u003e: This study aimed to investigate the prevalence and distribution of Work-related musculoskeletal disorders (WMSDs) among lead-acid battery manufacturing workers and to identify high-risk tasks and body regions through integrated epidemiological and ergonomic assessments, thereby establishing priorities for ergonomic intervention.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e We conducted a cross-sectional survey among 2,418 frontline workers from 10 lead–acid battery manufacturing enterprises in Jiangsu Province, China, using the Chinese Musculoskeletal Questionnaire (CMQ). Multivariable logistic regression was used to examine individual and work-related factors associated with WMSDs. Key production tasks were additionally assessed using video-based observation, with ergonomic hazards screened by the Swedish ergonomic hazard identification method and postural load quantified using the Rapid Upper Limb Assessment (RULA).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e The overall 12-month prevalence of WMSDs was 51.61%. The lower back and wrist/hand were the most frequently affected regions, followed by the shoulder and neck, with higher neck and shoulder prevalence among female workers. Manual handling of heavy loads and highly repetitive operations were associated with increased odds of both low back and wrist/hand WMSDs, whereas adequate rest time and physical exercise showed protective associations. Using the Swedish checklist, hazards were most frequently identified in the neck/shoulders/upper back (34/36 positions), upper limbs (29/36), and lower back (28/36). RULA classified 22/36 (61.11%) job positions as action levels III–IV, including 12/36 (33.33%) requiring immediate changes, indicating substantial postural load in key tasks.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e WMSDs impose a substantial burden in lead–acid battery manufacturing. Combining symptom surveillance with observational ergonomic assessment helps identify and prioritize high-risk tasks for targeted intervention, providing actionable evidence for workplace redesign and occupational health risk management in labor-intensive manufacturing settings.\u003c/p\u003e","manuscriptTitle":"Ergonomic Risk Prioritization of Work-Related Musculoskeletal Disorders in Lead-Acid Battery Manufacturing: A Cross-Sectional and Observational Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-19 10:37:43","doi":"10.21203/rs.3.rs-8654310/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"12202679372247442401381178381260718934","date":"2026-02-19T14:52:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"176546320915279804627384336763061929694","date":"2026-02-18T16:28:48+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-13T12:12:25+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-13T09:09:32+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-23T08:42:18+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-23T01:59:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Public Health","date":"2026-01-23T01:52:48+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pubh","sideBox":"Learn more about [BMC Public Health](http://bmcpublichealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pubh/default.aspx","title":"BMC Public Health","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2e5891e6-eb6a-42f2-827f-7d98a45306bd","owner":[],"postedDate":"February 19th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-19T10:37:44+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-19 10:37:43","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8654310","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8654310","identity":"rs-8654310","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}