Limitation of Ammonia Exposure among Workers in Fertilizers Industry Using Modern Modified Technology Towards Sustainability

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Elhadad, Taher A. Mansour, Ibrahim A. Elshibiny, Fadia A. Elmarakby This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5865743/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Background: Fertilizer production is a worldwide industry. Workers in the production process area may be exposed to mineral dust, water-soluble and insoluble compounds, nitric acid, nitrogen dioxide, nitrogen monoxide, ammonia (NH 3) , and hydrogen fluoride which might be emitted into the work environment in the different departments . Subjects and methods: The study was conducted in one of the modern nitrogenous fertilizer companies in Alexandria, Egypt. The company specializes in producing high quality nitrogenous fertilizers, mainly Granular Urea (46%) as a final product and Anhydrous NH 3 as an intermediate product using advanced technology. The study involved descriptive research adopts a quantitative and case study approach . Pre-designed and pre- tested structured two questionnaires for workers' data were used. The first questionnaire (A) was used for professional characters and occupational hygiene profile. The second questionnaire (B) was an optimal symptom score for employees’ complaints and their awareness about the occupational exposure to NH 3. NH 3 gas was measured in the ten different working areas in the factory. A direct reading- infrared spectrophotometry method was used. Results: The NH 3 synthesis factory is based on reliable and proven process steps controlled through automated operation of plants and machines. In the urea plant, the possible and available emission reduction techniques were used. All workers are males (100%). Current position includes specifications as technicians (n=125, 74.4 %) and engineers (n=43, 25.6%). The technicians' job duties are operation (n=77, 61.6%), production (n=2, 1.6%), maintenance (n=32, 25.6%) and inspection (n=14, 11.2%). Otherwise, the engineers ' job duties are operation (n=33, 76.7%), production (n=1, 2.3%), and maintenance (n=9, 20.9%). Work regime is day shift (n=119, 70.8%), and night shift (n=49, 29.2%). The total number of working hours/week ranges from 24-48 hours with a mean of 47.68±1.85 and a median of 48 hours. Considering the availability and usage of personal protective equipment (PPE) (n=167, 99.4%) and no smoking habits (n=168,100%), this reflects the increased knowledge and awareness, and the promoted safety culture of both the management and the employees. There is a statistically significant difference between the years of employment and the median for eyes, nose and sinuses symptoms (P = 0.001, 0.019 and 0.009 respectively ) . Regarding the mean concentration of NH 3 in the different working stations, it was found to be lower than the Threshold Limit Value- Time weighted average (TLV-TWA) of NH 3 which is 25 ppm. Conclusion: The current study highlighted the role of applying modern modified industry in limiting exposure to potential occupational hazards, improving the health of the workers, and achieving sustainability. Fertilizer production modern modified technology exposure to ammonia sustainability Egypt Figures Figure 1 Figure 2 Introduction The world depends on fertilizers to feed itself. Chemical fertilizers help to catalyze the green revolution, which dramatically increased global food production by leveraging new technologies and practices to increase yields and reduce prices. However, the increase in synthetic fertilizer use has come at an environmental price. Researchers have concluded that synthetic fertilizers are responsible for global greenhouse gases from the manufacture of the fertilizers and their breakdown by microbes in the soil after being applied on fields (Avşar 2024 ). Ammonia (NH 3 ) is chemically occurring within the atmosphere by nature, also as an important synthetic chemical. The greatest amount of NH 3 in the environment arises from the natural breakdown of manure, and dead plants and animals (Isaifan and Al-Thani). Manufactured NH 3 includes petrochemical fertilizers, which are synthetic products produced by using large quantities of petroleum and other fossil fuels; another sources are from power plants, mobile sources and other manufacturing emissions (Sabry 2015 ). More than 80 percent of the synthetic manufactured NH 3 is applied as a fertilizer (Soltanzadeh et al. 2023 ). Fertilizers production is a worldwide industry; the process is based on the dissolving of phosphate rock in mineral acid followed by neutralization, concentration, and granulation or pilling. Workers in the production process area may be exposed to mineral dust, water-soluble and insoluble compounds, nitric acid, nitrogen dioxide, nitrogen monoxide, NH 3 , and hydrogen fluoride which might be emitted into the work environment in the different departments (Khan et al. 2016 ). Exposure to NH 3 , within the range of 25–50 ppm, has been shown to irritate the upper airways in humans (Isaifan and Al-Thani). It interacts directly upon contact with accessible moisture within the eyes, skin, mouth, tract, and mainly mucous surfaces to compose caustic NH 3 water. Intensive exposure to NH 3 can be a reason for burning and irritation of the nose, throat and respiratory tract. This could cause airway destruction, leading to respiratory suffering or failure. In addition; NH 3 can be a source of olfactory failure or adaptation (Reis et al. 2024 ). Shrinking the industry’s environmental footprint and occupational impact in the face of these trends will require close collaboration among policy makers, multilateral lenders such as the International Finance Corporation (IFC), manufacturers of synthetic fertilizers, and the farmers and communities that use the fertilizers. The complex path to achieving NetZero fertilizer production underscores the challenges facing high-emissions industries as they transition to a more sustainable and circular future (International Finance Corporation (IFC) 2023 ). A new modification in NH 3 manufacture is recognized by substituting the melting and prilling units of finished-product urea with an environmentally friendly granulation process, which reduce the exposure to NH 3 (Khan et al. 2016 ). The aim of this study was to underline the importance of developing mitigation techniques to lower occupational and environmental impacts of NH 3 exposure in the fertilizers industry. Subjects and methods Study settings and design The study was conducted in one of the modern nitrogenous fertilizer companies in Alexandria, Egypt.The company specializes in producing high quality nitrogenous fertilizers, mainly Granular Urea as a final product and Anhydrous Ammonia as an intermediate product using advanced technology. This takes place in two main plants, which are NH 3 and urea plants. The study involves descriptive research adopting a quantitative and case study approach. Sample siz e and sampling techniques 1. The workers of the nitrogenous fertilizer company's locations such as operation, production, maintenance and inspection in Alexandria (Egypt) who were exposed to NH 3 (N= 300 workers) and accepted to participate in the case - study were included (n=168 workers; 56%). The participants (n=168), according to the working locations, were distributed as; 92 workers of the operation sector (54.8%), 31 workers of the production sector (18.5%), and 45 workers of maintenance and inspection sector (26.8%). Exclusion criterion: The workers on duty in the control rooms were excluded as they are expected to be unexposed to NH 3 . 2. The work environment of the nitrogenous fertilizer company's all productive locations (N= 10 locations; administration building, store house, urea/bulk store, water treatments utilities, compressor, NH 3 plant, urea synthesis, urea granulation, area between the NH 3 and urea plants, and finally the south area of the factory) were analyzed and NH 3 concentration was recorded in the selected locations monthly during a course of six months; from January to June 2021 considering the seasonal variations and the wind direction (n= 60 air samples). Data collection 1- Pre-designed and pre- tested structured two questionnaires for workers' data were used. The first questionnaire (A) was used for the professional characters and occupational hygiene profile (Osborne et al. 2023). The second questionnaire (B) was an optimal symptom score for employee's complaints and their awareness about the occupational exposure to NH 3 (Langenbruch et al. 2022). 2- NH 3 gas was measured in the ten different working areas in the factory. A direct reading method, Infrared spectrophotometry was used (LeBouf et al. 2013). Statistical analysis: Data was fed to the computer and analyzed using IBM SPSS software package version 20.0 . Qualitative data were described using number and percentage. The Kolmogorov-Smirnov test was used to verify the normality of distribution. Quantitative data were described using range (minimum and maximum), mean, and standard deviation, and median (inter quartile range [IQR]). The significance of the obtained results was judged at the 5% level. Results 1. Modern sustainable technologies for reducing occupational exposure to NH 3 in fertilizer plants The NH 3 synthesis factory is based on reliable and proven process steps controlled through automated operation of plants and machines. In NH 3 plant, the major features is the high-power primary reformer with cold outlet manifold, the secondary reformer with peripheral vortex burner, and the three-bed radial heat exchanger of magnetite with one or two synthesized transformers. In addition, the conventional process steps sequence for NH 3 synthesis which is one of Best Available Techniques (BAT ) reforming processes. The process undergoes major modifications to realize NH 3 emission reduction which are the steam reforming section including its waste heat recovery system, the carbon dioxide removal unit, and the NH 3 synthesis unit. In urea plant, the use of possible and available emission reduction techniques such as scrubbing the emission gases with the condensation process before inlet ventilation into the atmosphere, especially the acidic scrubber, using sulfuric or nitric acid producing ammonium sulfate or ammonium nitrate salts. In addition, wet washing of the prill tower and granulating plant to recover urea and NH 3 . In addition to Dual- pressure NH 3 manufacturing loop with distinctive secondary optimized design, dedicated waste heat boiler, and radial flow converters, The pollution prevention techniques include the recycling of NH 3 back to the process, using of post-combustion control technologies, as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) which are used to control nitrogen oxide emissions from fossil fuel combustion sources. Capture systems such as hoods which collect NH 3 emissions, and good maintenance practices implemented as well as adherence to safety practice guidelines to reduce and eliminate the occupational exposure hazards of NH 3 emissions. Summary of modern sustainable technologies for reducing occupational exposure to NH 3 fertilizer plants has shown in table (1). 2. Professional characteristics of the workers in fertilizers plant Table 2 shows the distribution of the workers of fertilizers plants according to their professional characteristics including gender, current position and job duties, work regime and the number of work hours per week. It is obvious from the table that all workers are males (100%). Current position, which includes specifications as technicians (n=125, 74.4 %) and engineers (n=43, 25.6%). The technicians' job duties are operation (n=77, 61.6%), production (n=2, 1.6%), maintenance (n=32, 25.6%) and inspection (n=14, 11.2%). Otherwise; the engineers’ job duties are operation (n=33, 76.7%), production (n=1, 2.3%), maintenance (n=9, 20.9%). Work regime is day shift (n=119, 70.8%), and night shift (n=49, 29.2%). The total number of working hours/week ranges from 24-48 hours with a mean of 47.68±1.85 and a median (IQR) of 48 hours. 3. Occupational Hygiene Profile of the workers in fertilizers plant Table 3 represents the occupational hygiene profile of the workers of fertilizers plants including work duration (years of employment), period of exposure to ammonia, the availability and usage of personal protective equipment (PPE), and smoking habit among workers. The work duration ranges from 5.0 to 17.0 years with a mean of 10.23±2.79 and a median (IQR) range from 7.50 to 12.0 and equal to 11.0 years. Considering the exposure to NH 3 ; the majority of the employees have already exposed with a percent of 97.6 % (n=164). As regards the healthy habits; the majority of the workers (n=147, 99.4%) have reported regular use of PPE. The most frequent types of PPE used include gloves (95.8%, n=161), goggles (88.7%, n=149), safety boot (95.8%, n=161), suit (73.2%, n=123) and apron (74.4%, n=125). In addition, All the workers are never smokers (100%, n=168), table 3. 4. Occupational health complaints Table 4 reveals the role of the worker's work duration (years of employment) in relation to the occupational health complaints and the overall total score of the symptoms. The worker’s duration is categorized as; 15 years. The majority of the eyes, nose, and sinuses symptoms were within the workers having (10 -15) years of employment where the median (IQR) was 22.22, 33.33, and 22.22 years respectively. There is a statistically significant difference between the years of employment and eyes, nose and sinuses symptoms (P = 0.001, 0.019 and 0.009 respectively ). In addition; there is also a statistically significant difference between the overall total score of workers' symptoms and the worker's work duration as the most suffering workers are those of work duration of 10 – 15 years with a median (IQR) of 16.67 years;( P=0.004). Otherwise, according to the breathing symptoms among the workers, there is no statistically significant difference between the worker's work duration (years) and the breathing symptoms (P = 0.997, 0.621 respectively ) respectively. 5. NH 3 concentrations Figure 1 presents the concentration of NH 3 detected monthly at ten workplace stations during the course of six months starting from January till June 2020. The highest concentrations are found in the station between NH 3 and urea plant [ranged from (0.98±0.02) to (1.03±0.03) ppm] and the area at the south of the factory [ranged from 0.99± 0.02 to 1.07±0.030 ppm] through the period of measurements. Otherwise, NH 3 has not been detected in the administrative building (especially in January, March, May, and June) and in the store house (especially in January, March, and June). Regarding the mean concentration of NH 3 in the different working stations, it was found to be lower than the TLV-TWA of 25 ppm. According to figure 2, there is a slight decrease in the mean concentration of NH 3 during versus winter (January and February); versus spring months (March and April) and the summer months (May and June) especially in NH 3 plant (0.76 ± 0.11 and 0.62 ± 0.10 ppm) in winter; versus (0.86 ± 0.09 and 0.84 ± 0.08 ppm) in Spring and (0.83 ± 0.05 and 0.81 ± 0.03 ppm) in Summer, Urea synthesis (0.82 ± 0.11 and 0.87± 0.07 ppm) in winter; versus (0.93 ± 0.05 and 1.00 ± 0.01 ppm) in Spring and (0.95 ± 0.07 and 0.95 ± 0.06 ppm ) in Summer , and in Urea granulation (0.73 ± 0.10 and 0.73 ± 0.05 ppm) in winter; versus (0.95 ± 0.07 and 0.93 ± 0.05 ppm) in Spring and (0.98 ± 0.02 and 0.98 ± 0.01 ppm) in Summer. There is a statistically significant difference between the concentrations of NH 3 within the different locations in the different months ( p <0.001 ). Discussion Nitrogenous fertilizer industry faces an occupational and environmental health impact challenge that workers may expose to NH 3 gas in the production process. Implementation of cleaner technologies and best available techniques in the modern nitrogenous fertilizer industries minimize occupational exposure to NH 3 gas and led to reduce Occupational hazards and consequently the environmental impact (Gezerman and Çorbacıoğlu 2016 ). Concerning the job qualifications in this occupation; the current study has shown that all the workers were males (100%), similar results were achieved in a study of occupational injuries in a fertilizer company in Egypt with a percent of 98.4% (Nm et al. 2017 ). In addition; the majority of the working force are technicians (75.6%), these results were consistent with the study conducted in fertilizer factory in Asyut city (Egypt) stated that about 73.5% of workers were technicians (Elwardany and Mohammed 2020 ), and the significantly higher participation of workers job duties was in the operational process ;for both technicians (n = 77,61.6%) and engineers (n = 33,76.7%), Table 2 . This complies with the study conducted in Iran where the studied population consisted of 67 (54%) male operational workers (high exposed group) and 57 (46%) male repair & maintenance workers (low exposed group) who were selected as exposed group (Neghab et al. 2018 ). As regards the work duration (years of employment) and its impact on health complaints; the present study has declared that the majority of the employees (n = 100, 59.5%) practice their work within 10–15 years (Table 3 ). This is disagreed with the study reporting that 77% of workers had years of experience of at least 15 years (Saffree Jeffree et al. 2016 ). This also declares the finding that the highest median of different health complaints is within workers of 10–15 years of employment as the majority of the eyes, nose, and sinuses symptoms were within the workers having (10–15) years of employment. There is a statistically significant difference between the years of employment and the median for eyes, nose and sinuses symptoms (P = 0.001, 0.019 and 0.009 respectively ) , (Table 4 ). This finding is matching with the result of the study curried out in an ammonia factory in Elberga petroleum factory (Libya), where there is a significant relation between job duration and nose and eyes irritation ( P = 0.03,0.037 respectively) (Mohamed et al. 2018 ). Considering the availability and usage of PPE (n = 167,99.4%) and no smoking habits (n = 168,100%), this reflects the increased knowledge and awareness, and the promoted safety culture of both the management and the employees about the importance of using this equipment and its role in protection against possible potential occupational hazards in the work environment (Table 3 ). The variation in the % of using different types of PPT within the different studies is logic as it depends on the safety culture of both the employees and the management. In epidemiologic studies concerning the effect of exposure to NH 3 among the workers in nitrogenous fertilizer companies, it has been discussed that short-term peak exposure might cause different and more severe health effects than the same exposure with lower concentrations over a longer time period. This was due to that the peaks may produce an elevated dose at target organ or overloading repair and protective mechanisms (Hovland 2014 ). In the current study, it has found that the time-weighted averages for NH 3 emission concentration in the ten stations (in the different months) within the company have generally been below the limits; where, the TLV-TWA for NH 3 is 25 ppm. The highest concentrations are found in the station between NH 3 and urea plant [ranged from (0.98 ± 0.02) to (1.03 ± 0.03) ppm] and the area at the south of the factory [ranged from 0.99 ± 0.02 to 1.07 ± 0.030 ppm] through the period of measurements. This may be attributed to the fact that the most common winds in Alexandria are north - west to north (Fig. 1 ). There is a slight decrease in the mean concentration of NH 3 during winter (January and February); versus spring months (March and April) and the summer months (May and June) especially in NH 3 plant, Urea synthesis and in Urea granulation. This may be due to the role of increased temperature in making NH3 more volatile and predictable in the work environment (Fig. 2 ). Conclusion The current study highlighted the role of applying modern modified industry in limiting exposure to potential occupational hazards, improving the health of the workers, and achieving sustainability. Declarations Ethics approval The protocol was approved by the “Committee of Ethics of High Institute of Public Health”. Oral consent was obtained from all individuals who accepted to participate in the study. Confidentiality of data was ensured. Transcript sheets were analyzed anonymously. Each respondent was given a code number for identification. There was no conflict of interest. Consent to participate Not applicable Consent for publication Not applicable. Authors’ contributions Both authors (Safinaz M. Elhadad and Fadia A. Elmarakby) were involved in choosing the topic, writing the research proposal, and collecting data. The corresponding author analyzed data and wrote the results, discussion and the manuscript, Taher A. Mansour contributed to conceptualization, supervision, visualization, writing-review & editing. Ibrahim A. Elshibiny provided formal analysis, recommendations and suggestions by reviewing the manuscript. All authors reviewed and approved the final version. Funding The authors did not receive any financial support from any agency. Competing interests The authors declare that they do not have any financial or non-financial Competing interests. Availability of data and materials The datasets used and/or analyzed during the current study are accessible From the corresponding author upon reasonable request. References Avşar C (2024) Sustainable transition in the fertilizer industry: alternative routes to low-carbon fertilizer production. Int J Environ Sci Technol 21(11): 7837-7848. https://doi.org/10.1007/s13762-024-05607-7 . Elwardany S, Mohammed F (2020) Occupational hazards and quality of life among fertilizer factory workers in Assiut City. Egypt Nurs J 15: 1-8. https://doi.org/10.4103/ENJ.ENJ_31_17 . Gezerman AO, Çorbacıoğlu BD (2016) Best available techniques in the fertilizer production industry: A Review. Eur J Chem 7(2): 243-247. https://doi.org/10.5155/eurjchem.7.2.243-247.1411 . Hovland KH. (2014). Lung function and occupational exposure among nitrate fertiliser production employees. A three year follow-up study [Ph.D Thesis]. University of Oslo . International Finance Corporation (IFC) (2023) Strengthening Sustainability in the Fertilizer industry. IFC, Washington . Isaifan RJ, Al-Thani HG Action Taken to Reduce Air Pollution and Its One Health Impacts in MENA Countries. Springer Berlin Heidelberg, Berlin, Heidelberg, 1-35 . Khan AR, Al-Awadi L, Al-Rashidi MS (2016) Control of ammonia and urea emissions from urea manufacturing facilities of Petrochemical Industries Company (PIC), Kuwait. J Air Waste Manag Assoc 66(6): 609-618. https://doi.org/10.108 0/10962247.2016.1145154. Langenbruch A, Wüstenberg E, Wolf H, Augustin M (2022) Development and Validation Features of the Patient Benefit Index for the Treatment of Allergic Rhinoconjunctivitis with Allergen Immunotherapy. J Asthma Allergy 15: 611-621 . https://doi.org/10.2147/jaa.s357469 . LeBouf RF, Slaven JE, Coffey CC (2013) Effect of calibration environment on the performance of direct-reading organic vapor monitors. J Air Waste Manag Assoc 63(5): 528-533. https://doi.org/10.1080/10962247.2013.772 926. Mohamed H, Alfutmani A, Omar K (2018) Irritation Effects of Ammonia Gas on Workers in Ammonia Factory at Elberga Petroleum Company During 2017. Sch J Appl Sci Res 1: 54-58 . Neghab M, Mirzaei A, Kargar Shouroki F, Jahangiri M, Zare M, Yousefinejad S (2018) Ventilatory disorders associated with occupational inhalation exposure to nitrogen trihydride (ammonia). Ind Health 56(5): 427-435. https://doi.org/10.2486/indhealth.2018-0014 . Nm K, Abou El-Wafa Hs AE-W, A A-W (2017) Occupational injuries among workers in a nitrogenous fertilizers company, Egypt. Egypt J Occupat Med 41(1): 1-17. https://doi.org/10.21608/ejom.2017.958 . Osborne RH, Nelson LM, Fehnel S, Williams N, Bender RH, Ziemiecki R et al. (2023) Evaluation of symptoms in respiratory syncytial virus infection in adults: psychometric evaluation of the Respiratory Infection Intensity and Impact Questionnaire™ symptom scores. J Patient Rep Outcomes 7(1): 51. https://doi.org/10.1186/s41687-023-00593-9 . Reis T, Moura PC, Gonçalves D, Ribeiro PA, Vassilenko V, Fino MH et al. (2024) Ammonia Detection by Electronic Noses for a Safer Work Environment. Sensors (Basel) 24(10): 3152. https://doi.org/10.3390/s24103152 . Sabry A (2015) Synthetic fertilizers; role and hazards. Fertil Technol 1: 110-133 . Saffree Jeffree M, Ismail N, Awang Lukman K (2016) Hearing impairment and contributing factors among fertilizer factory workers. J Occup Health 58(5): 434-443. https://doi.org/10.1539/joh.16-0043-OA . Soltanzadeh A, Adeli SH, Sadeghi Yarandi M, Heidari H, Mahdinia M (2023) Does exposure to ammonia concentrations lower than the threshold limit value cause acute pulmonary effects? Toxicol Ind Health 39(8): 471-479. https://doi.org/10.1177/07482337231185463 . Tables Table 1. Modern sustainable Technologies for Reducing Occupational Exposure to Ammonia in Fertilizer Plants Serial No. Technology Description Effectiveness 1 Scrubbers Remove ammonia from exhaust gases through chemical absorption. Achieves up to 95% removal efficiency. 2 Ammonia Sensors Real-time monitoring and detection of ammonia leaks. Allows early detection and prevents exposure. 3 Closed-loop Systems Recycles ammonia within the production process to minimize emissions. Significantly reduces ammonia release. 4 Personal Protective Equipment (PPE) Advanced PPE, including respirators and ammonia-resistant suits. Reduces inhalation and skin exposure risks. 5 Automated Control Systems Automated systems that manage ammonia levels and detect leaks. Enhances safety through prompt responses. 6 Bio filtration Utilizes bio filters to biologically treat ammonia emissions. An efficient and eco-friendly solution. 7 Ventilation Systems Improved designs to effectively disperse ammonia. Lowers airborne ammonia concentrations. 8 Sealing and Insulation Advanced materials for sealing and insulating ammonia handling areas. Prevents leaks and minimizes exposure. 9 Catalytic Oxidation Converts ammonia into nitrogen and water using catalysts. Reduces ammonia concentration in emissions. 10 Ammonia Absorption Units Specialized units designed to absorb and neutralize ammonia. Highly effective in localized ammonia reduction. Table 2.Distribution of workers according to professional characteristics (n=168) professional characteristics No. % Gender Male 168 100.0 Female 00 0.0 Current position Job/Position Technician 125 74.4 Engineer 43 25.6 Total 168 100 Current Job duties Operation technician 77 61.6 Production technician 2 1.6 Maintenance technician 32 25.6 Inspection technician 14 11.2 Total 125 100.0 Operation engineer 33 76.7 Production engineer 1 2.3 Maintenance engineer 9 20.9 Total 43 100 Work Regime Day shift 119 70.8 Night shift 49 29.2 Total 168 100 Hours of Work per Week Min. – Max. 24.0 – 48.0 Mean ± SD. 47.86 ± 1.85 Median (IQR) 48.0 Table 3. Distribution of workers according to occupational hygiene profile (n=168) Occupational hygiene profile No. % Current job duties Operation technician 77 45.8 Production technician 2 1.2 Maintenance technician 32 19.0 Inspection technician 14 8.3 Operation engineer 33 19.6 Production engineer 1 0.6 Maintenance engineer 9 5.4 Total 168 100 Work duration (years) 15 9 5.4 Min. – Max. 5.0 – 17.0 Mean ± SD. 10.23 ± 2.79 Median (IQR) 11.0 (7.50–12.0) Exposure to ammonia No 4 2.4 Yes 164 97.6 Period of exposure to ammonia (hrs. /day) Min. – Max. 12.0 – 12.0 Mean ± SD. 12.0 ± 0.0 Median (IQR) 12.0 Using personal protective equipment No 1 0.6 Yes 167 99.4 Total 168 100 Types of personal protective equipment used Gloves 161 95.8 Goggle 149 88.7 Boot 161 95.8 Air respirator 65 38.7 Mask 99 58.9 Hat 77 45.8 Suit 123 73.2 Apron 125 74.4 Smoking history Never smokers 168 100.0 Ex-smokers 0 0.0 Present smokers 0 0.0 Total 168 100 Table 4: Relation between job duration (years) and the occupational health complaints (n=168) % Score of symptoms job duration (years) H P 15 (n = 9) Eyes Min. – Max. 0.0 – 44.44 0.0 – 55.56 0.0 – 33.33 14.571 * 0.001 * Mean ± SD. 9.04 ± 13.13 18.89 ±15.99 11.11 ±14.70 Median 0.0 22.22 0.0 Nose Min. – Max. 0.0 – 66.67 0.0 – 75.0 0.0 – 58.33 7.921 * 0.019 * Mean ± SD. 18.64 ± 14.63 25.42 ± 15.86 24.07 ± 21.02 Median 16.67 33.33 16.67 Sinuses Min. – Max. 0.0 – 44.44 0.0 – 44.44 0.0 – 44.44 9.339 * 0.009 * Mean ± SD. 14.88 ± 14.39 23.33 ± 16.82 18.52 ± 18.43 Median 11.11 22.22 11.11 Breathing at awakening or during the day Min. – Max. 0.0 – 33.33 0.0 – 33.33 0.0 – 41.67 0.007 0.997 Mean ± SD. 4.52 ± 7.63 5.25 ± 9.22 6.48 ± 13.68 Median 0.0 0.0 0.0 Breathing at night Min. – Max. 0.0 – 25.0 0.0 – 33.33 0.0 – 33.33 0.953 0.621 Mean ± SD. 1.69 ± 5.31 2.08 ± 5.60 4.63 ± 11.11 Median 0.0 0.0 0.0 Overall total score Min. – Max. 0.0 – 38.89 0.0 – 42.59 0.0 – 42.59 11.171 * 0.004 * Mean ± SD. 9.53 ± 8.15 14.35 ± 9.23 12.76 ± 13.50 Median 7.41 16.67 5.56 H: H for Kruskal Wallis test p: p value for association between different categories *: Statistically significant at p ≤ 0.05 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 06 Feb, 2025 Editor assigned by journal 06 Feb, 2025 Submission checks completed at journal 06 Feb, 2025 First submitted to journal 20 Jan, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-5865743","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":412120070,"identity":"1482914f-e550-4bdc-b37c-42d1b732da22","order_by":0,"name":"Safinaz M. Elhadad","email":"data:image/png;base64,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","orcid":"","institution":"Arab Academy for Science, Technology and Maritime Transport","correspondingAuthor":true,"prefix":"","firstName":"Safinaz","middleName":"M.","lastName":"Elhadad","suffix":""},{"id":412120071,"identity":"0ddc7a58-43d7-4083-9d53-45d6debd4b82","order_by":1,"name":"Taher A. Mansour","email":"","orcid":"","institution":"Alexandria University","correspondingAuthor":false,"prefix":"","firstName":"Taher","middleName":"A.","lastName":"Mansour","suffix":""},{"id":412120072,"identity":"24d95aa7-99e1-454e-aee3-3a3777272c8f","order_by":2,"name":"Ibrahim A. Elshibiny","email":"","orcid":"","institution":"Alexandria University","correspondingAuthor":false,"prefix":"","firstName":"Ibrahim","middleName":"A.","lastName":"Elshibiny","suffix":""},{"id":412120073,"identity":"e277b849-135e-4b00-b8d3-cabbd4e47abb","order_by":3,"name":"Fadia A. Elmarakby","email":"","orcid":"","institution":"Professor of Occupational Hygiene and Air pollution, Alexandria University","correspondingAuthor":false,"prefix":"","firstName":"Fadia","middleName":"A.","lastName":"Elmarakby","suffix":""}],"badges":[],"createdAt":"2025-01-20 12:08:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5865743/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5865743/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":75896298,"identity":"65ac7a7b-4f36-4faa-9cbe-9489419a8302","added_by":"auto","created_at":"2025-02-10 10:33:15","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":125270,"visible":true,"origin":"","legend":"\u003cp\u003eAmmonia concentrations in different stations in modern modified nitrogenous fertilizer factory\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5865743/v1/f7b345e8d9e378a26ce808c2.png"},{"id":75896296,"identity":"80f4a32f-0ab6-40ae-8a05-62ac17e5805d","added_by":"auto","created_at":"2025-02-10 10:33:15","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":126339,"visible":true,"origin":"","legend":"\u003cp\u003eAmmonia concentrations during six months in different stations in modern modified nitrogenous fertilizer factory\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5865743/v1/9b8e1a532fc0807fdbbe964b.png"},{"id":75898632,"identity":"dbb01778-c3f3-4f69-9654-236baa9a2e45","added_by":"auto","created_at":"2025-02-10 10:49:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1597279,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5865743/v1/0ce0bf53-4c4f-4108-afb7-f48326434eb3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Limitation of Ammonia Exposure among Workers in Fertilizers Industry Using Modern Modified Technology Towards Sustainability","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe world depends on fertilizers to feed itself. Chemical fertilizers help to catalyze the green revolution, which dramatically increased global food production by leveraging new technologies and practices to increase yields and reduce prices. However, the increase in synthetic fertilizer use has come at an environmental price. Researchers have concluded that synthetic fertilizers are responsible for global greenhouse gases from the manufacture of the fertilizers and their breakdown by microbes in the soil after being applied on fields (Avşar \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAmmonia (NH\u003csub\u003e3\u003c/sub\u003e) is chemically occurring within the atmosphere by nature, also as an important synthetic chemical. The greatest amount of NH\u003csub\u003e3\u003c/sub\u003e in the environment arises from the natural breakdown of manure, and dead plants and animals (Isaifan and Al-Thani). Manufactured NH\u003csub\u003e3\u003c/sub\u003e includes petrochemical fertilizers, which are synthetic products produced by using large quantities of petroleum and other fossil fuels; another sources are from power plants, mobile sources and other manufacturing emissions (Sabry \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). More than 80 percent of the synthetic manufactured NH\u003csub\u003e3\u003c/sub\u003e is applied as a fertilizer (Soltanzadeh et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFertilizers production is a worldwide industry; the process is based on the dissolving of phosphate rock in mineral acid followed by neutralization, concentration, and granulation or pilling. Workers in the production process area may be exposed to mineral dust, water-soluble and insoluble compounds, nitric acid, nitrogen dioxide, nitrogen monoxide, NH\u003csub\u003e3\u003c/sub\u003e, and hydrogen fluoride which might be emitted into the work environment in the different departments (Khan et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eExposure to NH\u003csub\u003e3\u003c/sub\u003e, within the range of 25\u0026ndash;50 ppm, has been shown to irritate the upper airways in humans (Isaifan and Al-Thani). It interacts directly upon contact with accessible moisture within the eyes, skin, mouth, tract, and mainly mucous surfaces to compose caustic NH\u003csub\u003e3\u003c/sub\u003e water. Intensive exposure to NH\u003csub\u003e3\u003c/sub\u003e can be a reason for burning and irritation of the nose, throat and respiratory tract. This could cause airway destruction, leading to respiratory suffering or failure. In addition; NH\u003csub\u003e3\u003c/sub\u003e can be a source of olfactory failure or adaptation (Reis et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eShrinking the industry\u0026rsquo;s environmental footprint and occupational impact in the face of these trends will require close collaboration among policy makers, multilateral lenders such as the International Finance Corporation (IFC), manufacturers of synthetic fertilizers, and the farmers and communities that use the fertilizers. The complex path to achieving NetZero fertilizer production underscores the challenges facing high-emissions industries as they transition to a more sustainable and circular future (International Finance Corporation (IFC) \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). A new modification in NH\u003csub\u003e3\u003c/sub\u003e manufacture is recognized by substituting the melting and prilling units of finished-product urea with an environmentally friendly granulation process, which reduce the exposure to NH\u003csub\u003e3\u003c/sub\u003e (Khan et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The aim of this study was to underline the importance of developing mitigation techniques to lower occupational and environmental impacts of NH\u003csub\u003e3\u003c/sub\u003e exposure in the fertilizers industry.\u003c/p\u003e"},{"header":"Subjects and methods","content":"\u003cp\u003e\u003cstrong\u003eStudy settings and design\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted in one of the modern nitrogenous fertilizer companies in Alexandria, Egypt.The company specializes in producing high quality nitrogenous fertilizers, mainly Granular Urea as a final product and Anhydrous Ammonia as an intermediate product using advanced technology. This takes place in two main plants, which are NH\u003csub\u003e3\u003c/sub\u003e and urea plants. The study involves descriptive research adopting a quantitative and case study approach.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSample siz\u003c/strong\u003e\u003cstrong\u003ee and sampling techniques \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e1. The workers of the nitrogenous fertilizer company\u0026apos;s locations such as operation, production, maintenance and inspection in Alexandria (Egypt) who were exposed to NH\u003csub\u003e3\u003c/sub\u003e (N= 300 workers) and accepted to participate in the case - study were included (n=168 workers; 56%). \u003c/p\u003e\n\u003cp\u003eThe participants (n=168), according to the working locations, were distributed as; 92 workers of the operation sector (54.8%), 31 workers of the production sector (18.5%), and 45 workers of maintenance and inspection sector (26.8%). \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExclusion criterion:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe workers on duty in the control rooms were excluded as they are expected to be unexposed to NH\u003csub\u003e3\u003c/sub\u003e.\u003c/p\u003e\n\u003cp\u003e2. The work environment of the nitrogenous fertilizer company\u0026apos;s all productive locations (N= 10 locations; administration building, store house, urea/bulk store, water treatments utilities, compressor, NH\u003csub\u003e3\u003c/sub\u003e plant, urea synthesis, urea granulation, area between the NH\u003csub\u003e3\u003c/sub\u003e and urea plants, and finally the south area of the factory) were analyzed and NH\u003csub\u003e3\u003c/sub\u003e concentration was recorded in the selected locations monthly during a course of six months; from January to June 2021 considering the seasonal variations and the wind direction (n= 60 air samples). \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData collection \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e1- Pre-designed and pre- tested structured two questionnaires for workers\u0026apos; data were used. The first questionnaire (A) was used for the professional characters and occupational hygiene profile (Osborne et al. 2023). The second questionnaire (B) was an optimal symptom score for employee\u0026apos;s complaints and their awareness about the occupational exposure to NH\u003csub\u003e3\u003c/sub\u003e (Langenbruch et al. 2022).\u003c/p\u003e\n\u003cp\u003e2- NH\u003csub\u003e3\u003c/sub\u003e gas was measured in the ten different working areas in the factory. A direct reading method, Infrared spectrophotometry was used (LeBouf et al. 2013).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData was fed to the computer and analyzed using IBM SPSS software package version 20.0\u003cstrong\u003e\u003cem\u003e. \u003c/em\u003e\u003c/strong\u003eQualitative data were described using number and percentage. The Kolmogorov-Smirnov test was used to verify the normality of distribution. Quantitative data were described using range (minimum and maximum), mean, and standard deviation, and median (inter quartile range [IQR]). The significance of the obtained results was judged at the 5% level. \u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003e1. Modern sustainable technologies for reducing occupational exposure to \u003c/strong\u003eNH\u003csub\u003e3\u003c/sub\u003e\u003cstrong\u003e in fertilizer plants\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe NH\u003csub\u003e3\u003c/sub\u003e synthesis factory is based on reliable and proven process steps controlled through automated operation of plants and machines. In NH\u003csub\u003e3\u003c/sub\u003e plant, the major features is the high-power primary reformer with cold outlet manifold, the secondary reformer with peripheral vortex burner, and the three-bed radial heat exchanger of magnetite with one or two synthesized transformers. In addition, the conventional process steps sequence for NH\u003csub\u003e3\u003c/sub\u003e synthesis which is one of Best Available Techniques (BAT\u003cstrong\u003e) \u003c/strong\u003ereforming processes. The process undergoes major modifications to realize NH\u003csub\u003e3\u003c/sub\u003e emission reduction which are the steam reforming section including its waste heat recovery system, the carbon dioxide removal unit, and the NH\u003csub\u003e3\u003c/sub\u003e synthesis unit. \u003c/p\u003e\n\u003cp\u003eIn urea plant, the use of possible and available emission reduction techniques such as scrubbing the emission gases with the condensation process before inlet ventilation into the atmosphere, especially the acidic scrubber, using sulfuric or nitric acid producing ammonium sulfate or ammonium nitrate salts. In addition, wet washing of the prill tower and granulating plant to recover urea and NH\u003csub\u003e3\u003c/sub\u003e. \u003c/p\u003e\n\u003cp\u003eIn addition to Dual- pressure NH\u003csub\u003e3\u003c/sub\u003e manufacturing loop with distinctive secondary optimized design, dedicated waste heat boiler, and radial flow converters, The pollution prevention techniques include the recycling of NH\u003csub\u003e3\u003c/sub\u003e back to the process, using of post-combustion control technologies, as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) which are used to control nitrogen oxide emissions from fossil fuel combustion sources. Capture systems such as hoods which collect NH\u003csub\u003e3\u003c/sub\u003e emissions, and good maintenance practices implemented as well as adherence to safety practice guidelines to reduce and eliminate the occupational exposure hazards of NH\u003csub\u003e3\u003c/sub\u003e emissions. Summary of modern sustainable technologies for reducing occupational exposure to NH\u003csub\u003e3\u003c/sub\u003e fertilizer plants has shown in table (1). \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. Professional characteristics of the workers in fertilizers plant\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 2 shows the distribution of the workers of fertilizers plants according to their professional characteristics including gender, current position and job duties, work regime and the number of work hours per week. It is obvious from the table that all workers are males (100%). Current position, which includes specifications as technicians (n=125, 74.4 %) and engineers (n=43, 25.6%). The technicians\u0026apos; job duties are operation (n=77, 61.6%), production (n=2, 1.6%), maintenance (n=32, 25.6%) and inspection (n=14, 11.2%). Otherwise; the engineers\u0026rsquo; job duties are operation (n=33, 76.7%), production (n=1, 2.3%), maintenance (n=9, 20.9%). Work regime is day shift (n=119, 70.8%), and night shift (n=49, 29.2%). The total number of working hours/week ranges from 24-48 hours with a mean of 47.68\u0026plusmn;1.85 and a median (IQR) of 48 hours. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. Occupational Hygiene Profile of the workers in fertilizers plant\u003c/strong\u003e\u003cstrong\u003e\u003cspan dir=\"RTL\"\u003e \u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 3 represents the occupational hygiene profile of the workers of fertilizers plants including work duration (years of employment), period of exposure to ammonia, the availability and usage of personal protective equipment (PPE), and smoking habit among workers. The work duration ranges from 5.0 to 17.0 years with a mean of 10.23\u0026plusmn;2.79 and a median (IQR) range from 7.50 to 12.0 and equal to 11.0 years. Considering the exposure to NH\u003csub\u003e3\u003c/sub\u003e; the majority of the employees have already exposed with a percent of 97.6 % (n=164). \u003c/p\u003e\n\u003cp\u003eAs regards the healthy habits; the majority of the workers (n=147, 99.4%) have reported regular use of PPE. The most frequent types of PPE used include gloves (95.8%, n=161), goggles (88.7%, n=149), safety boot (95.8%, n=161), suit (73.2%, n=123) and apron (74.4%, n=125). In addition, All the workers are never smokers (100%, n=168), table 3. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4. Occupational health complaints\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 4 reveals the role of the worker\u0026apos;s work duration (years of employment) in relation to the occupational health complaints and the overall total score of the symptoms. The worker\u0026rsquo;s duration is categorized as; \u0026lt;10, (10 - 15), or \u0026gt;15 years. The majority of the eyes, nose, and sinuses symptoms were within the workers having (10 -15) years of employment where the median (IQR) was 22.22, 33.33, and 22.22 years respectively. There is a statistically significant difference between the years of employment and eyes, nose and sinuses symptoms \u003cstrong\u003e\u003cem\u003e(P = 0.001, 0.019 and 0.009 \u003c/em\u003erespectively\u003cem\u003e).\u003c/em\u003e\u003c/strong\u003eIn addition; there is also a statistically significant difference between the overall total score of workers\u0026apos; symptoms and the worker\u0026apos;s work duration as the most suffering workers are those of work duration of 10 \u0026ndash; 15 years with a median (IQR) of 16.67 years;(\u003cstrong\u003e\u003cem\u003eP=0.004).\u003c/em\u003e\u003c/strong\u003e Otherwise, according to the breathing symptoms among the workers, there is no statistically significant difference between the worker\u0026apos;s work duration (years) and the breathing symptoms \u003cstrong\u003e\u003cem\u003e(P = 0.997, 0.621 respectively\u003c/em\u003e\u003c/strong\u003e) respectively. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5. NH\u003csub\u003e3 \u003c/sub\u003econcentrations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 1 presents the concentration of NH\u003csub\u003e3\u003c/sub\u003e detected monthly at ten workplace stations during the course of six months starting from January till June 2020. The highest concentrations are found in the station between NH\u003csub\u003e3 \u003c/sub\u003eand urea plant [ranged from (0.98\u0026plusmn;0.02) to (1.03\u0026plusmn;0.03) ppm] and the area at the south of the factory [ranged from 0.99\u0026plusmn; 0.02 to 1.07\u0026plusmn;0.030 ppm] through the period of measurements. Otherwise, NH\u003csub\u003e3\u003c/sub\u003e has not been detected in the administrative building (especially in January, March, May, and June) and in the store house (especially in January, March, and June). Regarding the mean concentration of NH\u003csub\u003e3\u003c/sub\u003e in the different working stations, it was found to be lower than the TLV-TWA of 25 ppm. \u003c/p\u003e\n\u003cp\u003eAccording to figure 2, there is a slight decrease in the mean concentration of NH\u003csub\u003e3\u003c/sub\u003e during versus winter (January and February); versus spring months (March and April) and the summer months (May and June) especially in NH\u003csub\u003e3\u003c/sub\u003e plant (0.76 \u0026plusmn; 0.11 and 0.62 \u0026plusmn; 0.10 ppm) in winter; versus (0.86 \u0026plusmn; 0.09 and 0.84 \u0026plusmn; 0.08 ppm) in Spring and (0.83 \u0026plusmn; 0.05 and 0.81 \u0026plusmn; 0.03 ppm) in Summer, Urea synthesis (0.82 \u0026plusmn; 0.11 and 0.87\u0026plusmn; 0.07 ppm) in winter; versus (0.93 \u0026plusmn; 0.05 and 1.00 \u0026plusmn; 0.01 ppm) in Spring and (0.95 \u0026plusmn; 0.07 and 0.95 \u0026plusmn; 0.06 ppm ) in Summer , and in Urea granulation (0.73 \u0026plusmn; 0.10 and 0.73 \u0026plusmn; 0.05 ppm) in winter; versus (0.95 \u0026plusmn; 0.07 and 0.93 \u0026plusmn; 0.05 ppm) in Spring and (0.98 \u0026plusmn; 0.02 and 0.98 \u0026plusmn; 0.01 ppm) in Summer. There is a statistically significant difference between the concentrations of NH\u003csub\u003e3\u003c/sub\u003e within the different locations in the different months (\u003cstrong\u003e\u003cem\u003ep\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003e\u0026lt;0.001\u003c/em\u003e\u003c/strong\u003e). \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eNitrogenous fertilizer industry faces an occupational and environmental health impact challenge that workers may expose to NH\u003csub\u003e3\u003c/sub\u003e gas in the production process. Implementation of cleaner technologies and best available techniques in the modern nitrogenous fertilizer industries minimize occupational exposure to NH\u003csub\u003e3\u003c/sub\u003e gas and led to reduce Occupational hazards and consequently the environmental impact (Gezerman and \u0026Ccedil;orbacıoğlu \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eConcerning the job qualifications in this occupation; the current study has shown that all the workers were males (100%), similar results were achieved in a study of occupational injuries in a fertilizer company in Egypt with a percent of 98.4% (Nm et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). In addition; the majority of the working force are technicians (75.6%), these results were consistent with the study conducted in fertilizer factory in Asyut city (Egypt) stated that about 73.5% of workers were technicians (Elwardany and Mohammed \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), and the significantly higher participation of workers job duties was in the operational process ;for both technicians (n\u0026thinsp;=\u0026thinsp;77,61.6%) and engineers (n\u0026thinsp;=\u0026thinsp;33,76.7%), Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. This complies with the study conducted in Iran where the studied population consisted of 67 (54%) male operational workers (high exposed group) and 57 (46%) male repair \u0026amp; maintenance workers (low exposed group) who were selected as exposed group (Neghab et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAs regards the work duration (years of employment) and its impact on health complaints; the present study has declared that the majority of the employees (n\u0026thinsp;=\u0026thinsp;100, 59.5%) practice their work within 10\u0026ndash;15 years (Table \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This is disagreed with the study reporting that 77% of workers had years of experience of at least 15 years (Saffree Jeffree et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis also declares the finding that the highest median of different health complaints is within workers of 10\u0026ndash;15 years of employment as the majority of the eyes, nose, and sinuses symptoms were within the workers having (10\u0026ndash;15) years of employment. There is a statistically significant difference between the years of employment and the median for eyes, nose and sinuses symptoms \u003cb\u003e(P\u0026thinsp;=\u0026thinsp;0.001, 0.019 and 0.009\u003c/b\u003e \u003cb\u003erespectively\u003c/b\u003e\u003cb\u003e)\u003c/b\u003e, (Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). This finding is matching with the result of the study curried out in an ammonia factory in Elberga petroleum factory (Libya), where there is a significant relation between job duration and nose and eyes irritation (\u003cb\u003eP\u0026thinsp;=\u0026thinsp;0.03,0.037\u003c/b\u003e respectively) (Mohamed et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eConsidering the availability and usage of PPE (n\u0026thinsp;=\u0026thinsp;167,99.4%) and no smoking habits (n\u0026thinsp;=\u0026thinsp;168,100%), this reflects the increased knowledge and awareness, and the promoted safety culture of both the management and the employees about the importance of using this equipment and its role in protection against possible potential occupational hazards in the work environment (Table \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The variation in the % of using different types of PPT within the different studies is logic as it depends on the safety culture of both the employees and the management.\u003c/p\u003e \u003cp\u003eIn epidemiologic studies concerning the effect of exposure to NH\u003csub\u003e3\u003c/sub\u003e among the workers in nitrogenous fertilizer companies, it has been discussed that short-term peak exposure might cause different and more severe health effects than the same exposure with lower concentrations over a longer time period. This was due to that the peaks may produce an elevated dose at target organ or overloading repair and protective mechanisms (Hovland \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). In the current study, it has found that the time-weighted averages for NH\u003csub\u003e3\u003c/sub\u003e emission concentration in the ten stations (in the different months) within the company have generally been below the limits; where, the TLV-TWA for NH\u003csub\u003e3\u003c/sub\u003e is 25 ppm.\u003c/p\u003e \u003cp\u003eThe highest concentrations are found in the station between NH\u003csub\u003e3\u003c/sub\u003e and urea plant [ranged from (0.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02) to (1.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03) ppm] and the area at the south of the factory [ranged from 0.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 to 1.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.030 ppm] through the period of measurements. This may be attributed to the fact that the most common winds in Alexandria are north - west to north (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThere is a slight decrease in the mean concentration of NH\u003csub\u003e3\u003c/sub\u003e during winter (January and February); versus spring months (March and April) and the summer months (May and June) especially in NH\u003csub\u003e3\u003c/sub\u003e plant, Urea synthesis and in Urea granulation. This may be due to the role of increased temperature in making NH3 more volatile and predictable in the work environment (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe current study highlighted the role of applying modern modified industry in limiting exposure to potential occupational hazards, improving the health of the workers, and achieving sustainability.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eThe protocol was approved by the \u0026ldquo;Committee of Ethics of High Institute of Public Health\u0026rdquo;.\u003c/li\u003e\n \u003cli\u003eOral consent was obtained from all individuals who accepted to participate in the study.\u003c/li\u003e\n \u003cli\u003eConfidentiality of data was ensured. \u0026nbsp;\u003c/li\u003e\n \u003cli\u003eTranscript sheets were analyzed anonymously. \u0026nbsp;\u003c/li\u003e\n \u003cli\u003eEach respondent was given a code number for identification.\u003c/li\u003e\n \u003cli\u003eThere was no conflict of interest.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBoth authors (Safinaz M. Elhadad and Fadia A. Elmarakby) were involved in choosing the topic, writing the research proposal, and collecting data. The corresponding author analyzed data and wrote the results, discussion and the manuscript,\u0026nbsp;Taher A. Mansour contributed to conceptualization, supervision, visualization, writing-review \u0026amp; editing. Ibrahim A. Elshibiny provided formal analysis, recommendations and suggestions by reviewing the manuscript. All authors reviewed and approved the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors did not receive any financial support from any agency.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they do not have any financial or non-financial Competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are accessible\u003c/p\u003e\n\u003cp\u003eFrom the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAvşar C (2024) Sustainable transition in the fertilizer industry: alternative routes to low-carbon fertilizer production. Int J Environ Sci Technol\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e21(11): 7837-7848. https://doi.org/10.1007/s13762-024-05607-7\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eElwardany S, \u0026nbsp;Mohammed F (2020) Occupational hazards and quality of life among fertilizer factory workers in Assiut City. Egypt Nurs J\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e15: 1-8. https://doi.org/10.4103/ENJ.ENJ_31_17\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eGezerman AO, \u0026nbsp;\u0026Ccedil;orbacıoğlu BD (2016) Best available techniques in the fertilizer production industry: A Review. Eur\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003eJ Chem\u003cem\u003e\u0026nbsp; \u0026nbsp;\u003c/em\u003e7(2): 243-247. https://doi.org/10.5155/eurjchem.7.2.243-247.1411\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eHovland KH. (2014). \u003cem\u003eLung function and occupational exposure among nitrate fertiliser production employees. A three year follow-up study\u003c/em\u003e [Ph.D Thesis]. University of Oslo\u003cspan dir=\"RTL\"\u003e. \u0026nbsp;\u0026nbsp;\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eInternational Finance Corporation (IFC) (2023) Strengthening Sustainability in the Fertilizer industry. IFC, Washington\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eIsaifan RJ, \u0026nbsp;Al-Thani HG \u0026nbsp; \u0026nbsp;Action Taken to Reduce Air Pollution and Its One Health Impacts in MENA Countries. Springer Berlin Heidelberg, Berlin, Heidelberg, \u0026nbsp;1-35\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eKhan AR, Al-Awadi L, \u0026nbsp;Al-Rashidi MS (2016) Control of ammonia and urea emissions from urea manufacturing facilities of Petrochemical Industries Company (PIC), Kuwait. J Air Waste Manag Assoc\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e66(6): 609-618. https://doi.org/10.108\u003cspan dir=\"RTL\"\u003e0/10962247.2016.1145154.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eLangenbruch A, W\u0026uuml;stenberg E, Wolf H, \u0026nbsp;Augustin M (2022) Development and Validation Features of the Patient Benefit Index for the Treatment of Allergic Rhinoconjunctivitis with Allergen Immunotherapy. J Asthma Allergy\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e15: 611-621\u003cspan dir=\"RTL\"\u003e.\u0026nbsp;\u003c/span\u003ehttps://doi.org/10.2147/jaa.s357469\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eLeBouf RF, Slaven JE, \u0026nbsp;Coffey CC (2013) Effect of calibration environment on the performance of direct-reading organic vapor monitors. J Air Waste Manag Assoc\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e63(5): 528-533. https://doi.org/10.1080/10962247.2013.772\u003cspan dir=\"RTL\"\u003e926.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eMohamed H, Alfutmani A, \u0026nbsp;Omar K (2018) Irritation Effects of Ammonia Gas on Workers in Ammonia Factory at Elberga Petroleum Company During 2017. Sch J Appl Sci Res\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e1: 54-58\u003cspan dir=\"RTL\"\u003e.\u0026nbsp;\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eNeghab M, Mirzaei A, Kargar Shouroki F, Jahangiri M, Zare M, \u0026nbsp;Yousefinejad\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003eS (2018) Ventilatory disorders associated with occupational inhalation exposure to nitrogen trihydride (ammonia). Ind Health\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e56(5): 427-435. https://doi.org/10.2486/indhealth.2018-0014\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eNm K, Abou El-Wafa Hs AE-W, \u0026nbsp;A A-W (2017) Occupational injuries among workers in a nitrogenous fertilizers company, Egypt. Egypt J Occupat Med\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e41(1): 1-17. https://doi.org/10.21608/ejom.2017.958\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eOsborne RH, Nelson LM, Fehnel S, Williams N, Bender RH, Ziemiecki R et al. (2023) Evaluation of symptoms in respiratory syncytial virus infection in adults: psychometric evaluation of the Respiratory Infection Intensity and Impact Questionnaire\u0026trade; symptom scores. J Patient Rep Outcomes\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e7(1): 51. https://doi.org/10.1186/s41687-023-00593-9\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eReis T, Moura PC, Gon\u0026ccedil;alves D, Ribeiro PA, Vassilenko V, Fino MH et al. (2024) Ammonia Detection by Electronic Noses for a Safer Work Environment. Sensors (Basel)\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e24(10): 3152. https://doi.org/10.3390/s24103152\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eSabry A (2015) Synthetic fertilizers; role and hazards. Fertil Technol\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e1: 110-133\u003cspan dir=\"RTL\"\u003e.\u0026nbsp;\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eSaffree Jeffree M, Ismail N, \u0026nbsp;Awang Lukman K (2016) Hearing impairment and contributing factors among fertilizer factory workers. J Occup Health\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e58(5): 434-443. https://doi.org/10.1539/joh.16-0043-OA\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003eSoltanzadeh A, Adeli SH, Sadeghi Yarandi M, Heidari H, \u0026nbsp;Mahdinia M (2023) Does exposure to ammonia concentrations lower than the threshold limit value cause acute pulmonary effects? Toxicol Ind Health\u003cem\u003e\u0026nbsp;\u0026nbsp;\u003c/em\u003e39(8): 471-479. https://doi.org/10.1177/07482337231185463\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1. Modern sustainable Technologies for Reducing Occupational Exposure to Ammonia in Fertilizer Plants\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSerial No.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTechnology\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEffectiveness\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScrubbers\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eRemove ammonia from exhaust gases through chemical absorption.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eAchieves up to 95% removal efficiency.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAmmonia Sensors\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eReal-time monitoring and detection of ammonia leaks.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eAllows early detection and prevents exposure.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eClosed-loop Systems\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eRecycles ammonia within the production process to minimize emissions.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eSignificantly reduces ammonia release.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePersonal Protective Equipment (PPE)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eAdvanced PPE, including respirators and ammonia-resistant suits.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eReduces inhalation and skin exposure risks.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAutomated Control Systems\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eAutomated systems that manage ammonia levels and detect leaks.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eEnhances safety through prompt responses.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBio filtration\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eUtilizes bio filters to biologically treat ammonia emissions.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eAn efficient and eco-friendly solution.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVentilation Systems\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eImproved designs to effectively disperse ammonia.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eLowers airborne ammonia concentrations.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSealing and Insulation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eAdvanced materials for sealing and insulating ammonia handling areas.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003ePrevents leaks and minimizes exposure.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e9\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCatalytic Oxidation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eConverts ammonia into nitrogen and water using catalysts.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eReduces ammonia concentration in emissions.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e10\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAmmonia Absorption Units\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eSpecialized units designed to absorb and neutralize ammonia.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003eHighly effective in localized ammonia reduction.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.Distribution of workers according to professional characteristics (n=168)\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eprofessional\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;characteristics\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eNo.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e100.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCurrent position\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eJob/Position\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eTechnician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e74.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eEngineer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e25.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCurrent Job duties\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eOperation technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e61.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eProduction technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e1.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMaintenance technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e25.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eInspection technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e11.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e100.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eOperation engineer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e76.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eProduction engineer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e2.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMaintenance engineer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e20.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWork Regime\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eDay shift\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e119\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e70.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eNight shift\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e29.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHours of Work per Week\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 191px;\"\u003e\n \u003cp\u003e24.0 \u0026ndash; 48.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 191px;\"\u003e\n \u003cp\u003e47.86 \u0026plusmn; 1.85\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eMedian (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 191px;\"\u003e\n \u003cp\u003e48.0\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Distribution of workers according to occupational hygiene profile (n=168)\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOccupational\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;hygiene\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;profile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003eNo.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCurrent job duties\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eOperation technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e45.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eProduction technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMaintenance technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e19.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eInspection technician\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e8.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eOperation engineer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e19.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eProduction engineer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMaintenance engineer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e5.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWork duration (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003e\u0026lt;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e35.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003e10-15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e59.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003e\u0026gt;15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e5.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e5.0 \u0026ndash; 17.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e10.23 \u0026plusmn; 2.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMedian (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e11.0 (7.50\u0026ndash;12.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eExposure to ammonia\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e164\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e97.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePeriod of exposure to ammonia (hrs. /day)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e12.0 \u0026ndash; 12.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e12.0 \u0026plusmn; 0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eMedian (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 191px;\"\u003e\n \u003cp\u003e12.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUsing personal protective equipment\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 354px;\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e167\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e99.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"bottom\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTypes of personal protective equipment used\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eGloves\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e161\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e95.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eGoggle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e149\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e88.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eBoot\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e161\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e95.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eAir respirator\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e38.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eMask\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e58.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eHat\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e45.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eSuit\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e123\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e73.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 357px;\"\u003e\n \u003cp\u003eApron\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e74.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" style=\"width: 545px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSmoking history\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 357px;\"\u003e\n \u003cp\u003eNever smokers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e100.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 357px;\"\u003e\n \u003cp\u003eEx-smokers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 357px;\"\u003e\n \u003cp\u003ePresent smokers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 357px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4: Relation between job duration (years) and the occupational health complaints (n=168)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 29px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Score of symptoms\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ejob duration\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 9px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eH\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 9px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;10\u003cbr\u003e\u0026nbsp;(n = 59)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e(10 -15)\u003cbr\u003e\u0026nbsp;(n = 100)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026gt;15\u003c/strong\u003e\u003cstrong\u003e\u003cbr\u003e\u0026nbsp;(n = 9)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEyes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 44.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 55.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 33.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e14.571\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e9.04 \u0026plusmn; 13.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e18.89 \u0026plusmn;15.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e11.11 \u0026plusmn;14.70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e22.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNose\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 66.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 75.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 58.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e7.921\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.019\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e18.64 \u0026plusmn; 14.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e25.42 \u0026plusmn; 15.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e24.07 \u0026plusmn; 21.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e16.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e33.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e16.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSinuses\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 44.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 44.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 44.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e9.339\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.009\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e14.88 \u0026plusmn; 14.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e23.33 \u0026plusmn; 16.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e18.52 \u0026plusmn; 18.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e11.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e22.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e11.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBreathing at awakening or during the day\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 33.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 33.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 41.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.997\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e4.52 \u0026plusmn; 7.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e5.25 \u0026plusmn; 9.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e6.48 \u0026plusmn; 13.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBreathing at night\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 25.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 33.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 33.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.953\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.621\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e1.69 \u0026plusmn; 5.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e2.08 \u0026plusmn; 5.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e4.63 \u0026plusmn; 11.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOverall total score\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMin. \u0026ndash; Max.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 38.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 42.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0 \u0026ndash; 42.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e11.171\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0.004\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e9.53 \u0026plusmn; 8.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e14.35 \u0026plusmn; 9.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e12.76 \u0026plusmn; 13.50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e7.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e16.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e5.56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eH: H for \u003cstrong\u003eKruskal Wallis test\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;p: p value for association between different categories \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; *: Statistically significant at p \u0026le; 0.05 \u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-environment","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Environment](https://www.springer.com/44274/)","snPcode":"44274","submissionUrl":"https://submission.nature.com/new-submission/44274/3","title":"Discover Environment","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Fertilizer production, modern modified technology, exposure to ammonia, sustainability, Egypt","lastPublishedDoi":"10.21203/rs.3.rs-5865743/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5865743/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eFertilizer production is a worldwide industry. Workers in the production process area may be exposed to mineral dust, water-soluble and insoluble compounds, nitric acid, nitrogen dioxide, nitrogen monoxide, ammonia (NH\u003csub\u003e3)\u003c/sub\u003e, and hydrogen fluoride which might be emitted into the work environment in the different departments\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSubjects and methods: \u003c/strong\u003eThe study was conducted in one of the modern nitrogenous fertilizer companies in Alexandria, Egypt.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe company specializes in producing high quality nitrogenous fertilizers, mainly Granular Urea (46%) as a final product and Anhydrous NH\u003csub\u003e3\u003c/sub\u003e as an intermediate product using advanced technology. The study involved descriptive research adopts a quantitative and case study approach\u003cstrong\u003e. \u003c/strong\u003ePre-designed and pre- tested structured two questionnaires for workers' data were used. The first questionnaire (A) was used for professional characters and occupational hygiene profile. The second questionnaire (B) was an optimal symptom score for employees’ complaints\u0026nbsp;and their awareness about the occupational exposure to NH\u003csub\u003e3.\u003c/sub\u003e NH\u003csub\u003e3\u003c/sub\u003e gas was measured in the ten different working areas in the factory. \u0026nbsp;A direct reading- infrared spectrophotometry method was used.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e The NH\u003csub\u003e3\u003c/sub\u003e synthesis factory is based on reliable and proven process steps controlled through automated operation of plants and machines. In the urea plant, the possible and available emission reduction techniques were used. All workers are males (100%). Current position includes specifications as technicians (n=125, 74.4 %) and engineers (n=43, 25.6%). The technicians' job duties are operation (n=77, 61.6%), production (n=2, 1.6%), maintenance (n=32, 25.6%) and inspection (n=14, 11.2%). Otherwise, the engineers ' job duties are operation (n=33, 76.7%), production (n=1, 2.3%), and maintenance (n=9, 20.9%). Work regime is day shift (n=119, 70.8%), and night shift (n=49, 29.2%). The total number of working hours/week ranges from 24-48 hours with a mean of 47.68±1.85 and a median of 48 hours. Considering the availability and usage of personal protective equipment (PPE) (n=167, 99.4%) and no smoking habits (n=168,100%), this reflects the increased knowledge and awareness, and the promoted safety culture of both the management and the employees. There is a statistically significant difference between the years of employment and the median for eyes, nose and sinuses symptoms \u003cem\u003e\u003cstrong\u003e(P = 0.001, 0.019 and 0.009 \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003erespectively\u003c/strong\u003e\u003cem\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003c/em\u003e. Regarding the mean concentration of NH\u003csub\u003e3\u003c/sub\u003e in the different working stations, it was found to be lower than the Threshold Limit Value- Time weighted average (TLV-TWA) of \u0026nbsp;NH\u003csub\u003e3 \u003c/sub\u003ewhich is 25 ppm.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eThe current study highlighted the role of applying modern modified industry in limiting exposure to potential occupational hazards, improving the health of the workers, and achieving sustainability.\u003c/p\u003e","manuscriptTitle":"Limitation of Ammonia Exposure among Workers in Fertilizers Industry Using Modern Modified Technology Towards Sustainability","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-10 10:33:10","doi":"10.21203/rs.3.rs-5865743/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-02-06T13:48:41+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-02-06T13:44:09+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-02-06T10:20:56+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Environment","date":"2025-01-20T11:59:37+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-environment","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Environment](https://www.springer.com/44274/)","snPcode":"44274","submissionUrl":"https://submission.nature.com/new-submission/44274/3","title":"Discover Environment","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1ab40b7e-50bb-4fd4-b2c2-71061fc7e8f9","owner":[],"postedDate":"February 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-06-16T18:23:23+00:00","versionOfRecord":[],"versionCreatedAt":"2025-02-10 10:33:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5865743","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5865743","identity":"rs-5865743","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}