Mycotoxins Present in the Indoor Air of a Music School Repurposed from an Atomic Shelter

Mycotoxins Present in the Indoor Air of a Music School Repurposed from an Atomic Shelter | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Mycotoxins Present in the Indoor Air of a Music School Repurposed from an Atomic Shelter Ivona Majić, Adela Krivohlavek, Elvira Kovač Andrić, Ranka Godec This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5632354/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Clean air is essential for human well-being, especially indoors. Indoor air quality has a significant impact on human health and there is concern about the health effects of exposure to airborne bacteria and fungi. The World Health Organization has warned of adverse health effects associated with building moisture and biological agents. Mold growth due to indoor moisture affects a significant percentage of buildings worldwide, leading to increased health risks, especially for children. It is crucial to work on implementing effective solutions to create healthier indoor environments for children worldwide. This study investigates the adverse health effects of total indoor air bacteria and molds and potential exposure to mycotoxins, which are products of airborne molds, on school-aged children. The study was conducted in the Music School in Zagreb, where children spend a few hours a day in a space originally designed as a nuclear shelter, without external openings, and the findings strongly suggest that the airborne mold levels in the music classroom are consistently distributed due to the shared air conditioning and ventilation system shared with the outdoor environment.The presence of a few isolated molds, with lower concentrations than outdoors, may be attributable to the regular use of air dehumidifiers. Low concentrations of airborne mold may pose a health risk for atopic children who are particularly susceptible to fungal spores, especially in environments contaminated with mycotoxin-producing fungi, further contribute to indoor air pollution. poor sanity conditions indoor spaces children's health mesophilic bacteria mold Figures Figure 1 Figure 2 Figure 3 Figure 4 Highlights • Role of airborne mycotoxins in children's institutions-impact on children's health • Health risks related to mycotoxin exposure by inhalation in the child population • Role of air dehumidifiers in reducing the concentration of mycotoxins in the air • Connection between airborne mycotoxins and those isolated from human urine • The harmful impact of low concentrations of indoor mold mycotoxins producers on health INTRODUCTION Clean air is vital for human well-being (World Health Organization 2009 , 2010 ). People spend the majority of our time indoors (80–95%), breathing in 10–14 m 3 of air per day (Awad and Farag 1999 ; Shiaka and Yakubu 2013 ; Hayleeyesus and Manaye 2014 ; Uzoechi et al. 2017 ). It is essential that enclosed environments like homes, offices, and schools provide a healthy and safe atmosphere for peoples overall progress and success (Naga Madhan Mohan et al. 2014 ; Enitan et al. 2017 ). The quality of indoor air significantly impacts human health (World Health Organization 2009 , 2010 ). Concerns have arisen regarding the health effects of exposure to airborne bacteria and fungi. The World Health Organization (WHO) has cautioned about the adverse health effects associated with building moisture and biological agents, including respiratory symptoms, allergies, asthma, and immune system disorders (Mendell et al. 2011 ). Indoor sources of airborne microorganisms, along with outdoor air conditions, play a significant role in determining air quality (Rintala et al. 2008 ; Bowers et al. 2012 ). Furthermore, natural ventilation and factors such as lack of thermal insulation and poor ventilation can contribute to the excessive growth of microorganisms indoors, creating a potential risk to vulnerable groups such as children and the elderly (Daisey et al. 2003 ; World Health Organization 2009 , 2010 ). It's important to recognize that indoor air quality can have a significant impact on the health of children, particularly in relation to asthma, allergies, and respiratory issues (Cooley et al. 2004 ; Bornehag et al. 2005 ; Mendell 2007 ; Thacher et al. 2017 ). Studies have revealed that factors such as biological agents, ventilation systems, moisture, and mold problems in buildings can contribute to increased health risks for children. Research conducted in Sweden found that attending daycare was associated with a higher risk of respiratory tract infections and eczema in children (Hagerhed-Engman et al. 2006 ). Mold growth due to indoor dampness affects a significant percentage of buildings worldwide, particularly in Australia, Europe, North America, India, and Japan (World Health Organization 2009 ). These issues are prevalent in both developed and developing countries, urban and rural areas, and in various climate zones. It's crucial to work towards implementing effective solutions to address these challenges in order to create healthier indoor environments for children worldwide. The presence of indoor dampness leading to mold growth affects a significant percentage of buildings in various regions, including Australia, Europe, North America, India, and Japan (World Health Organization 2009 ). This issue is more prevalent in areas near rivers, lakes, wetlands, coastal regions, or places previously affected by floods (Omebeyinje et al. 2021 ). Mold-affected apartments have been documented in both developed and developing countries, urban and rural areas, and in all types of residential buildings and climate zones. Recent studies indicate that indoor moisture and mold indicators impact up to 21% of European homes (Haverinen-Shaughnessy 2012 ; Norbäck et al. 2017 ), up to 27% of Northern European homes (Bornehag et al. 2004 ; Gunnbjörnsdóttir et al. 2006 ), up to 47% of American homes (Brunekreef et al. 1989 ; Moseley-Braun et al. 1995 ; Hu et al. 1997 ; Maier et al. 1997 ; Slezak et al. 1998 ; Girman et al. 2002 ; Freeman et al. 2003 ; Stark et al. 2003 ; Bornehag et al. 2004 ; Gunnbjörnsdóttir et al. 2006 ; Sun and Sundell 2013 ), and 12–78% of homes in New Zealand (Howden-Chapman et al. 2007 ; Ingham et al. 2019 ). In urban, suburban, and rural China, up to 12% of residential buildings have indoor mold, and up to 55% of homes are affected by window condensation (Liu et al. 2015 ; Weir 2019 ; Cai et al. 2020 ). A global study in both high-income and low-income countries revealed that up to 47% of homes reported the presence of indoor dampness or mold (Li et al. 2015 ). Although there are limited studies in tropical regions, a recent survey in southern India found that 50% of homes had moisture problems (Cai et al. 2019 ). A study in northern Thailand reported indoor mold in 7.1% of homes and water leakage in 28.2% of homes, occurring in both the "dry" and "rainy" seasons (Weinmayr et al. 2013 ). Despite improvements in building standards in developed countries (Zock et al. 2002 ; Dewsbury et al. 2016a , b ; Prapamontol et al. 2021 ) and an increased understanding of key risk factors for mold growth, mold-affected buildings remain a persistent and frequent problem worldwide. The presence of mold in closed residential spaces is the direct outcome of several contributing factors, including poor construction, inadequate maintenance, improper use of space, insufficient heating, and poor ventilation (Keall et al. 2010 ; Kembel et al. 2012 ; Fisk 2015 ; Telfar-Barnard et al. 2017 ; Sharpe et al. 2018 ). Indoor mold growth is directly linked to the availability of sufficient moisture. Prolonged exposure to moisture within a building can significantly impact insulation, leading to increased energy consumption (Antova et al. 2008 ), reduced lifespan of building materials, and considerable repair and maintenance costs (Richardson 2002 ; PricewaterhouseCoopers (PWC) 2009 ; Alencastro et al. 2019 ). It is widely acknowledged that dampness and mold in living spaces have detrimental effects on the health of occupants (Cox-Ganser 2015 ). Various studies have indicated that moisture and visible mold inside buildings can lead to adverse health effects, particularly focusing on asthma, allergic reactions, respiratory infections, and respiratory symptoms. However, research on rare clinical conditions resulting from mold exposure remains relatively underexplored (Fisk et al. 2010 ; Mendell et al. 2011 ; Cox‐Ganser 2015; Major and Boese 2017 ). The most effective measure to mitigate moisture and mold in indoor environments involves the limitation of liquid and vapor moisture within building materials (Adams et al. 2016 ), across the building, or within individual apartments (Mendell et al. 2018 ). Understanding the multiple causes of excessive moisture and taking preventive measures is crucial to mitigating the risk of exposure to mold, moisture, and mold-related indoor contaminants. Previous international research has identified eight key categories as risk factors for indoor mold, encompassing climate, housing conditions, socioeconomic factors, construction characteristics, tenant behavior, location, building maintenance, and urbanization (World Health Organization 2009 ; Keall et al. 2010 ; Fisk 2015 ). The most common risk factors for mold growth include living conditions and construction characteristics of the building (Coulburn and Miller 2022 ). The air quality in schools can be more of a concern compared to other types of buildings due to higher population density, inadequate ventilation, and poor maintenance (Pegas et al. 2011 ). Poor indoor air quality can lead to health issues and increased absenteeism among children, who are more vulnerable to environmental hazards (Godoi et al. 2009 ; Pegas et al. 2011 ). It is important to collect data on bacteria and fungi in the air to protect students from potential health risks (Salin et al. 2021 ). Music schools, in particular, may have poor air quality and insufficient space, which can increase the risk of negative health effects. There is also concern about mycotoxin-producing fungi in damp indoor spaces, such as schools, which could have harmful effects on health. Research is needed to understand the health effects of indoor mycotoxins on sensitive populations. A significant number of children attend music schools, which may have microclimatic conditions that are not suitable and are used by a large number of people in a confined space. There are limited studies that examine the dispersion of microorganisms during playing and singing. Existing data primarily focus on measuring dispersion with individual instruments and modeling the dispersion of potentially infectious droplets and aerosols (Zayas et al. 2012 ; Bourouiba et al. 2014 ). Research has shown that singing can contribute to the spread of tuberculosis, as the percentage of droplets emitted into the air during singing is significantly higher than during normal conversation and is comparable to that released by coughing (Johnson et al. 2011 ). Consequently, music schools with poor indoor air quality may pose an increased risk of negative health effects. Fungal metabolites (mycotoxins) can be harmful to human and animal health and are commonly associated with mold-contaminated food. Some of the most well- known mycotoxins are aflatoxins, ochratoxin A, fumonisins, zearalenone, trichothecenes, sterigmatocystin and gliotoxin (Khan et al. 2024 ). In addition, molds and fungi can also produce volatile organic compounds (VOCs) during their metabolism (Bennett and Inamdar 2015 ). These compounds include various alcohols, ketones, aldehydes, esters, terpenes and others. These VOCs can contribute to the musty odor indoors and affect air quality. Concern has been raised about exposure to mycotoxin-producing fungi in enclosed spaces, such as damp apartments, offices, and schools. Although most mycotoxins that contaminate food and feed are rarely found indoors, the toxicological properties of indoor mycotoxins could have negative health effects on sensitive populations. The genera of fungi Penicillium and Aspergillus are the primary contaminants of food and animal feed and are the dominant indoor species in moist areas. Mold enters the body through the nose via the olfactory neurons, which directly communicate with the brain. Mycotoxins induce toxicological effects similar to those associated with brain disorders such as oxidative stress and inflammation. Even a small amount of mold growth in the air conditioners and their ducts or the panels inside the buildings and even the cars cause the occupants to be chronically exposed to and constantly inhaling spores and mycotoxins, which causes illness (Ehsanifar et al. 2023 ). Further research is needed on the health effects of mycotoxins from these indoor species, as well as the mycotoxins of Stachybotrys and Chaetomium mushrooms, due to potential long-term chronic exposure (Jarvis and Miller 2005 ). Aspergillus, Penicillium, Fusarium, S. Chartarum (also known as S. Atra ), Paecilomyces , and Trichoderma species are important toxigenic fungi from a public health perspective. These fungi are linked to harmful effects on the health of humans and animals, causing specific organ damage and diseases that are typically neither allergic nor infectious (Li et al. 2015 ). A recent investigation by the Australian government into illnesses related to biotoxins found that tenants living in mold-infested apartments experienced negative health impacts (Hyvönen et al. 2020 ). This drew attention to the dangers of poorly researched airborne mycotoxins. This study is one of the first to investigate airborne bacteria and fungi in connection with possible mycotoxin exposure in children in Croatia. The focus of this study was to investigate the levels of bacteria and fungi present in the air at a music school that has been treated for moisture, and to explore any potential correlation between the airborne fungi and mycotoxins identified in the urine of a child with autism spectrum disorder (ASD) who regularly attends the school. Mold spores and mycotoxins can trigger or worsen respiratory conditions such as asthma and allergies in children with autism, exacerbating cognitive and behavioral symptoms associated with autism and compromise the immune system, making children more susceptible to infections and inflammation (De Santis et al. 2017 ; Ratnaseelan et al. 2018 ; Serkan et al. 2021 ). Recent epidemiologic findings have shown a significant association between ASD and mycotoxin exposure; it reads as 1 in 36 children are affected by ASD that is caused/linked by mycotoxin exposure (Shaw et al. 2021 ; Maenner et al. 2023 ). The specific objectives of this investigation were as follows: 1. To quantify the concentrations of bacteria and fungi in the air that may have potential implications for human health; 2. To identify the types of fungi present; 3. To assess the influence of external concentrations of bacteria and fungi on indoor air quality; 4. To determine whether the mycotoxins identified in the child's with ASD urine can be associated with airborne fungi. MATERIALS AND METHODS In a Music school in Zagreb, air samples were collected as part of a microbiological study. The school is used by 20 students on a daily basis and is located in a space originally designed as an atomic shelter, without external openings. Within this space, an air dehumidifier operates continuously, and a AC (air conditioner) device was turned off during the measurement. Although there was a distinct moldy smell in the room, no visible mold was observed. The microclimatic conditions encountered are summarized in Table 1 . Table 1 Microclimatic conditions at the sampling locations, as well as the measured concentrations of CO 2 and PM particles Air temperature (°C) Relative Humidity (%Rh) Number of people present CO 2 (ppm) partices (PM) ≥ 1µm (Counts/m 3 ) entrance area of atomic shelter 15.6 41.2 3 698 982686 middle area of atomic shelter 15.8 41.5 3 702 1537103 rear area of atomic shelter 15.2 40.7 3 710 1225795 outside air 12.7 38 2 578 58657 The microbiological studies involved assessing the total number of mesophilic bacteria and molds. Air samples were collected using the SAS-360 DUO air sampler. The tested air volumes were 2 x 100 and 2 x 200 liters for each measurement location, and the sampling rate was 360 l/min. After sampling the air on nutrient media (International Organization for Standardization (ISO) 2011a , b ), the media were incubated at a specific temperature for a certain duration. Indoor air sampling was performed using a SAS 360 DUO sampler using the active SAS method on TSA (Tripton soy agar, LOT: 230718/21.10.2024) and DG18 agar (Dicloran 18% glycerol agar, LOT:180918/16.12.2024) (International Organization for Standardization (ISO) 2008 , 2009 , 2011a , b ). Additionally, outdoor air sampling was conducted in accordance with the standards ISO 16000-1 and ISO 16000-19 (International Organization for Standardization (ISO) 2004 , 2012 ). The evaluation of indoor air microbiological testing involves comparing microbiological indicators of outdoor and indoor air (Yassin and Almouqatea 2010 ). According to the Portuguese standard stated in Portugese standard nº 353-A/2013 (Ministérios do Ambiente Ordenamento do Território e Energia da Saúde e da Solidariedad Emprego e Segurança Social 2013 ), a concentration of the total number of bacteria in the indoor air must be lower than the outdoor concentration + 350 CFU/m 3 , and the mold concentration of the indoor air must be lower than that of the outdoor air (International Organization for Standardization (ISO) 2004 ). After sampling, nutrient media, TSA, and DG 18 are incubated. Nutrient media for determining the total number of bacteria (on TSA) are incubated at (37 ± 3) °C for 2 days. If there's no colony growth, incubation can be extended up to 7 days. Nutrient media for determining the total number of molds are incubated for 7 days at (25 ± 3) °C. DG 18 agar can be incubated for 10 days if further mold identification is necessary. The average number of bacteria and fungi is calculated as colony-forming units in 1 m 3 (CFU/m 3 ). The number of microorganisms counted on the surface of the nutrient medium must be corrected for the possibility of a statistical error that occurs due to the probability of the passage of different types of particles through the holes in the aspiration head of the instrument. The conversion formula is taken from the SAS Device User's Guide. The probable number (Pr) from the table is then used to calculate (CFU) per cubic meter of air sampled. Example of result calculation (Eq. 1): \(\:X=\frac{{P}_{r}\times\:1000}{V}\) [1] where is V - volume of sampled air P r - possible number of CFU obtained from the correction table X - no. CFU per m 3 of air According to the ISO 16000-17 standard (International Organization for Standardization (ISO) 2008 , 2009 ), the number of mold colonies counted on the nutrient medium surface does not need to be adjusted. The mold concentration per cubic meter of air is expressed by calculating the number of colonies for each identified species individually. Unidentified species are categorized as "others". The total mold colony count is the sum of identified mold species and "others". The total mold count (CFU) per cubic meter is calculated according to the equation (Eq. 2): C i = n CFU / V i [2] where is V i - volume of sampled air n CFU - number of CFU C i - no. CFU per m 3 of air As per the EN 13098 standard (European Standards 2019 ), the total number of microorganisms in the air is measured as the number of colonies per cubic meter of air (CFU/m 3 ). The main fungal isolates were identified using the Bruker MALDI Biotyper method. Parameters like relative humidity, temperature, and the number of people in the building were recorded during sampling. The MycoTOX Child Profile, a modern urine-based test, was used to accurately assess the levels of 11 different mycotoxins, including aflatoxin M1, ochratoxin A, gliotoxin, mycophenolic acid, and zearalenone. This profile utilizes liquid chromatography technology to detect free (unconjugated) mycotoxins even at low levels (Bennett and Klich 2003 ; Janik et al. 2020 ). RESULTS AND DISCUSSION The environmental survey was meticulously conducted during the spring season to evaluate and characterize the indoor air quality of the specified enclosed space. Throughout the assessment, the outdoor air temperature was measured at approximately 12.7°C, providing a baseline for comparison. In contrast, the indoor temperature within the enclosed environment fluctuated between 15.2°C and 15.7°C, indicating a regulated climate controlled by the building’s heating, ventilation, and air conditioning systems. Regarding relative humidity, the indoor levels exhibited variability between 40.7% and 41.2%. This variance was influenced by specific locations where air samples were collected, highlighting the spatial differences in humidity distribution within the space. For comparison, the outdoor relative humidity was found to be 39.1%, which serves as a reference point for evaluating the effectiveness of the indoor environmental controls. It is noteworthy that the enclosed area under investigation was equipped with both a dehumidifier and an air conditioning system. These systems are designed to manage and regulate indoor humidity levels, and their presence could significantly impact the indoor humidity measurements obtained during the survey. Additionally, the findings from the microbiological analysis, which provide critical insights into the indoor air quality, have been visually represented in Figs. 1 and 2 . These figures not only provide visual representation of the data but are also integral for a comprehensive understanding of the types and concentrations of microorganisms present, as well as the potential contaminants that may affect the overall indoor air quality of the environment surveyed. The investigation uncovered that the back area of the space was significantly tainted with bacteriological contamination, indicating the presence of various harmful bacteria that could pose health risks. This area’s conditions likely favored the proliferation of microbes, which can thrive in damp or poorly ventilated environments. In stark contrast, the entrance area revealed a troubling abundance of mold, which suggests that factors such as humidity, inadequate lighting, or insufficient airflow may have contributed to its growth. To accurately identify the specific types of mold and yeast present, researchers utilized the advanced Bruker MALDI Biotyper method, a sophisticated technique renowned for its ability to precisely identify microorganisms based on their unique protein profiles. Through this analysis, a remarkable array of microbial species was discovered, totaling 55 distinct types of mold alongside one type of yeast. Among the identified species was Aspergillus flavus , notorious for its potential to produce toxic aflatoxins that can contaminate food supplies. Penicillium verrucosum , which can also generate harmful mycotoxins, was likewise detected. The presence of Aspergillus fumigatus was noted, a mold well-known for its association with respiratory ailments, particularly in individuals with weakened immune systems. The catch-all category of Penicillium spp. pointed to several mold types typically found in indoor settings. Additionally, researchers found Alternaria alternata , a common allergenic mold that can trigger allergic reactions and asthma in sensitive individuals. Notably, they also isolated Candida albicans , a type of yeast that can lead to infections, particularly in those with compromised immune systems. Comprehensive details about these identified microorganisms, including their potential risks and impact on health, can be found in Table 2 . Table 2 Types of isolated molds in various locations within the investigated area. entrance area of atomic shelter middle area of atomic shelter rear area of atomic shelter Aspergillus flavus (11) Alternaria alternata (5) Penicillium spp (7) Penicillium spp (6) Penicillium verrucosum (12) Penicillium verrucosum (12) Aspergillus fumigatus (29) Aspergillus fumigatus (13) Aspergillus fumigatus (13) Candida albicans (3) Aspergillus flavus (10) Aspergillus flavus (10) Alternaria alternata (5) According to the Portuguese standard stated in Portugese standard nº 353-A/2013 (Ministérios do Ambiente Ordenamento do Território e Energia da Saúde e da Solidariedad Emprego e Segurança Social 2013 ), a thorough assessment of indoor air quality was conducted, focusing on the total number of bacteria and molds present. The results indicated that the measured levels of both microorganisms remained well within the specified reference values, indicating a safe indoor environment. The concentration of the total number of bacteria in the indoor air must be lower than the outdoor concentration + 350 CFU/m 3 , and the mold concentration of the indoor air must be lower than that of the outdoor air (International Organization for Standardization (ISO) 2004 ). This ensures that indoor spaces maintain a healthy atmosphere, effectively minimizing the risk of airborne bacterial proliferation. Similarly, regarding mold concentrations, it is essential that the levels inside the premises do not exceed those detected in the outdoor environment. This guideline serves to prevent potential health issues associated with mold exposure. Additionally, Fig. 4 provides a comprehensive overview of the elevated levels of mycotoxins that were isolated from the urine samples of the child with ASD in question. In one study, the comparison of urine and serum ochratoxin A levels in 52 children with ASD with healthy children was significant (De Santis et al. 2019 ). Also, in a cross-sectional study, the different mycotoxins levels (fumonisin B1, ochratoxin A, and aflatoxin M1) were notably higher in the urine and serum of 172 children with ASD compared to 61 healthy individuals (De Santis et al. 2017 ). These findings raise important considerations about possible exposure to harmful substances, warranting further investigation and attention to the child's environmental conditions. The presence of mycotoxins in urine is often a key indicator of exposure, making it crucial to monitor and address any potential sources in the child's surroundings. The quality of air within educational institutions, such as schools and kindergartens, is an area of significant concern and interest among researchers, given the vital role these environments play in the development and health of children. Children spend a considerable portion of their day in these settings, making it crucial to ensure that the air they breathe is free from harmful pollutants. Numerous research studies have been conducted to investigate various aspects of air quality, with a particular emphasis on microbiological pollution. This includes examining the types and concentrations of microorganisms, such as bacteria and fungi, that can adversely affect health and contribute to allergic reactions or respiratory issues. These studies have produced a wealth of valuable data that has been meticulously compiled and is presented in Table 3 . This table offers detailed and quantitative information regarding the levels of bacteria and fungi present in the airborne environment of educational facilities. It integrates findings from a diverse array of literature, encompassing various methodologies and conditions under which air samples were collected, thereby providing a comprehensive overview of the microbiological landscape in schools and kindergartens. The results underscore the necessity of continuous monitoring and improvement of air quality in these institutions, emphasizing their critical role in safeguarding the health and well-being of young learners and creating a conducive learning environment. Table 3 Information on the quantity of bacteria and fungi present in the air of school institutions (literature sources) Sampling site number of bacteria (CFU/m 3 ) number of fungi (CFU/m 3 ) references school corridors 7700–8200 (Karwowska 2003 ) laboratories 1600–2000 160–780 other rooms inside the school 100–1000 (Karbowska-Berent et al. 2011 ) lecture rooms 493 (Filipiak et al. 2004 ) classrooms 75 − 56 000 23-1400 (Enitan et al. 2017 ) school premises 0-550 (Meklin et al. 2002 ) Croatia currently lacks standards and regulations for microbiological contaminant levels in indoor air. According to the Portuguese standard (Ministérios do Ambiente Ordenamento do Território e Energia da Saúde e da Solidariedad Emprego e Segurança Social 2013 ), the total number of bacteria and molds in indoor air should not exceed specific reference values. Despite the levels in our research being below these reference values, we found yeasts and molds that could negatively impact health, particularly for individuals with compromised immune systems (Salin et al. 2017 ; Tuuminen et al. 2019 ). Scientific evidence suggests that exposure to moisture-related microbes and decay products from moisture-damaged building materials can lead to a range of health issues known as moisture and mold hypersensitivity syndrome (DMHS)(Valtonen 2017 ; Vaali et al. 2022 ). Prolonged exposure to these microbes and decay products may result in symptoms such as fatigue, neurological, gastrointestinal, musculoskeletal problems, and respiratory issues (Hyvönen et al. 2020 , 2021 ; Vornanen-Winqvist et al. 2020 ; Hyvonen et al. 2020 ; Vaali et al. 2022 ). Diagnosing DMHS currently relies on clinical observations and patient data, as a specific biomarker has not been developed. Continuous or cumulative exposure to moisture-related microbes and decay products can worsen symptoms and lead to irreversible multiorgan DMHS (Hyvönen et al. 2020 ; Vaali et al. 2022 ). Mycotoxins may also be effective in ASD. A study on 172 children with ASD with 61 controls showed significant differences comparing antibodies to mycotoxins between the 2 groups, and the ASD group indicated higher serum antibodies to mycotoxins (De Santis et al. 2019 ). Research findings from the Tufts University School of Medicine suggested that mycotoxins cause ASD. Mycotoxins, toxic byproducts of mold, can cause mycotoxicosis upon entering the body. To assess the risk of mold exposure in enclosed spaces, it is crucial to apply knowledge about agriculturally important toxins and conduct further research to understand the relationship between mycotoxin exposure and health issues (Cole and Cox 1981 ; Cole et al. 2003 ). Research is also needed to comprehend how various factors influence the outcomes of mold exposure. Additionally, it is important to note that people genetically predisposed to allergies and asthma may be more sensitive to mold and mildew spores, potentially contributing to upper respiratory tract problems, especially in children (Bornehag et al. 2004 ). While assessing the role of mold exposure in causing disease symptoms without direct measurement through biomarkers is challenging, there is a likelihood that toxins from building-associated fungi play a role in causing health issues. Further studies are required to understand the impact of low molecular weight toxins on lung biology (Miller et al. 2003 ) and to identify the types and amounts of toxin metabolites present in residential buildings. CONCLUSIONS The findings of the study reveal that the levels of airborne fungi in the music classroom exhibit a consistent distribution pattern. This pattern largely stems from the shared air-conditioning and ventilation system that connects the indoor environment to the outside atmosphere. The presence of a limited number of isolated mold species, which manifest at lower concentrations compared to outdoor levels, is largely due to the proactive use of air dehumidifiers within the classroom. These dehumidifiers help to minimize moisture, thereby reducing mold growth. However, some of the isolated molds possess the ability to produce mycotoxins - toxic compounds that are recognized for their harmful effects on both humans and animals. When these mycotoxins are released into the air, they can contribute to a range of detrimental health effects due to their toxic nature. The synergistic inhalation of these fungal byproducts can lead to various health problems, including respiratory irritation, general toxicity, and even more serious conditions such as teratogenicity (developmental issues), carcinogenicity (cancer risk), and immunosuppression (a weakened immune response). This situation poses a particularly significant risk for atopic children, who are more vulnerable to allergens and irritants, including fungal spores. In environments where mycotoxin-producing fungi are present, these children may experience exacerbated symptoms and complications that contribute to overall indoor air pollution. The potential link between mold exposure and ASD represents a significant shift in our understanding of this complex disorder. While more research is needed to fully elucidate the connection, the emerging evidence suggests that environmental factors, including mold exposure, may play a more significant role in ASD symptoms than previously thought.Given the potential health hazards associated with mycotoxins in enclosed spaces, needs further research. Given the potential health hazards associated with mycotoxins in enclosed spaces, there is an urgent call for further research. This research is essential to deepen our understanding of the dynamics of mycotoxins in indoor environments and to assess their potential adverse effects on human health, particularly among sensitive populations such as children. Declarations ACKNOWLEDGEMENT This activity was carried out within the “Food Safety and Quality Center” (KK.01.1.1.02.0004) project funded by the European Regional Development Fund and was performed using the facilities and equipment funded within the European Regional Development Fund project KK.01.1.1.02.0007 "Research and Education Centre of Environmental Health and Radiation Protection – Reconstruction and Expansion of the Institute for Medical Research and Occupational Health", and funded by the European Union – Next Generation EU (Program Contract of 8 December 2023, Class: 643-02/23-01/00016, Reg. no. 533-03-23-0006)-EnvironPollutHealth. 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J Allergy Clin Immunol 110:285–292. https://doi.org/10.1067/mai.2002.126383 Additional Declarations No competing interests reported. Supplementary Files GA.png Graphical abstract Cite Share Download PDF Status: Posted Version 1 posted 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-5632354","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":392281922,"identity":"f133402d-6219-4896-8508-0adf873e81c1","order_by":0,"name":"Ivona Majić","email":"","orcid":"","institution":"Andrija Štampar Teaching Institute of Public Health","correspondingAuthor":false,"prefix":"","firstName":"Ivona","middleName":"","lastName":"Majić","suffix":""},{"id":392281923,"identity":"17457b1d-3c4f-4f61-a168-f74f89ba7ea8","order_by":1,"name":"Adela Krivohlavek","email":"","orcid":"","institution":"Andrija Štampar Teaching Institute of Public Health","correspondingAuthor":false,"prefix":"","firstName":"Adela","middleName":"","lastName":"Krivohlavek","suffix":""},{"id":392281924,"identity":"889810d7-6e9e-4f3f-bfa3-a22c6357a9cc","order_by":2,"name":"Elvira Kovač Andrić","email":"","orcid":"","institution":"Josip Juraj Strossmayer University of Osijek","correspondingAuthor":false,"prefix":"","firstName":"Elvira","middleName":"Kovač","lastName":"Andrić","suffix":""},{"id":392281925,"identity":"1698279e-8752-4d9e-b54e-601a705cee0b","order_by":3,"name":"Ranka Godec","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAl0lEQVRIiWNgGAWjYJACCQYGGx4GZgY2krSkka7lMIgmUot5/+KDNz7UnJfRbWdge1xBjBaZG8+SLWccu81jdpiB3fAMUY6SOGMmzdsA1sIm2UC0lr8N50jRwt9jJs3YcIAkW9iSLXuOJQO1MLYRa8vhgzd+1NjZm50/fIw4LQwSCTAWI3EaGBj4DxCpcBSMglEwCkYuAACeICuRwPfJ7AAAAABJRU5ErkJggg==","orcid":"","institution":"Institute for Medical Research and Occupational 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classroom\u003c/p\u003e","description":"","filename":"Figure1aerobicmasophilicbacteria.png","url":"https://assets-eu.researchsquare.com/files/rs-5632354/v1/d4b5fa7fc4d938318c747696.png"},{"id":72334764,"identity":"40d6ace2-2357-4941-acac-f63d2dfcb947","added_by":"auto","created_at":"2024-12-25 15:39:26","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":92945,"visible":true,"origin":"","legend":"\u003cp\u003eTotal number of molds in different parts of the music classroom\u003c/p\u003e","description":"","filename":"Figure2molds.png","url":"https://assets-eu.researchsquare.com/files/rs-5632354/v1/9fdd532f1405f49a87375ebb.png"},{"id":72334767,"identity":"b8c1bb01-c4f0-41f9-a786-429249b4a85d","added_by":"auto","created_at":"2024-12-25 15:39:26","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3376527,"visible":true,"origin":"","legend":"\u003cp\u003eMolds on nutrient agar from sampled air in atomic shelter\u003c/p\u003e","description":"","filename":"Figure3agar.png","url":"https://assets-eu.researchsquare.com/files/rs-5632354/v1/4058346ef8d400e7b95a461d.png"},{"id":72336216,"identity":"a4ced062-104f-43b6-b63a-71f8192bd2ae","added_by":"auto","created_at":"2024-12-25 15:47:27","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":32073,"visible":true,"origin":"","legend":"\u003cp\u003eSummary of elevated results of mycotoxins isolated from the child's urine.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5632354/v1/dbf6c3e75eeb3a73a17808a7.png"},{"id":77131300,"identity":"ad596d48-3344-43d8-bce5-d667a00f8f2a","added_by":"auto","created_at":"2025-02-25 12:17:11","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4049532,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5632354/v1/0d30a2bf-800a-4271-9b34-6a42bdd25542.pdf"},{"id":72336214,"identity":"d44d3d93-9b03-44f1-b19c-2ac19d3fb18a","added_by":"auto","created_at":"2024-12-25 15:47:26","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1819758,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical abstract\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"GA.png","url":"https://assets-eu.researchsquare.com/files/rs-5632354/v1/93de8c74b0701affc93f97df.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Mycotoxins Present in the Indoor Air of a Music School Repurposed from an Atomic Shelter","fulltext":[{"header":"Highlights","content":"\u003cp\u003e\u0026bull; Role of airborne mycotoxins in children's institutions-impact on children's health\u003c/p\u003e\u003cp\u003e\u0026bull; Health risks related to mycotoxin exposure by inhalation in the child population\u003c/p\u003e\u003cp\u003e\u0026bull; Role of air dehumidifiers in reducing the concentration of mycotoxins in the air\u003c/p\u003e\u003cp\u003e\u0026bull; Connection between airborne mycotoxins and those isolated from human urine\u003c/p\u003e\u003cp\u003e\u0026bull; The harmful impact of low concentrations of indoor mold mycotoxins producers on health\u003c/p\u003e"},{"header":"INTRODUCTION","content":"\u003cp\u003eClean air is vital for human well-being (World Health Organization \u003cspan citationid=\"CR97\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, \u003cspan citationid=\"CR96\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). People spend the majority of our time indoors (80\u0026ndash;95%), breathing in 10\u0026ndash;14 m\u003csup\u003e3\u003c/sup\u003e of air per day (Awad and Farag \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Shiaka and Yakubu \u003cspan citationid=\"CR83\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Hayleeyesus and Manaye \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Uzoechi et al. \u003cspan citationid=\"CR90\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). It is essential that enclosed environments like homes, offices, and schools provide a healthy and safe atmosphere for peoples overall progress and success (Naga Madhan Mohan et al. \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Enitan et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The quality of indoor air significantly impacts human health (World Health Organization \u003cspan citationid=\"CR97\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, \u003cspan citationid=\"CR96\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Concerns have arisen regarding the health effects of exposure to airborne bacteria and fungi. The World Health Organization (WHO) has cautioned about the adverse health effects associated with building moisture and biological agents, including respiratory symptoms, allergies, asthma, and immune system disorders (Mendell et al. \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Indoor sources of airborne microorganisms, along with outdoor air conditions, play a significant role in determining air quality (Rintala et al. \u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Bowers et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Furthermore, natural ventilation and factors such as lack of thermal insulation and poor ventilation can contribute to the excessive growth of microorganisms indoors, creating a potential risk to vulnerable groups such as children and the elderly (Daisey et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; World Health Organization \u003cspan citationid=\"CR97\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, \u003cspan citationid=\"CR96\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). It's important to recognize that indoor air quality can have a significant impact on the health of children, particularly in relation to asthma, allergies, and respiratory issues (Cooley et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Bornehag et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Mendell \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Thacher et al. \u003cspan citationid=\"CR88\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Studies have revealed that factors such as biological agents, ventilation systems, moisture, and mold problems in buildings can contribute to increased health risks for children. Research conducted in Sweden found that attending daycare was associated with a higher risk of respiratory tract infections and eczema in children (Hagerhed-Engman et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Mold growth due to indoor dampness affects a significant percentage of buildings worldwide, particularly in Australia, Europe, North America, India, and Japan (World Health Organization \u003cspan citationid=\"CR97\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). These issues are prevalent in both developed and developing countries, urban and rural areas, and in various climate zones. It's crucial to work towards implementing effective solutions to address these challenges in order to create healthier indoor environments for children worldwide. The presence of indoor dampness leading to mold growth affects a significant percentage of buildings in various regions, including Australia, Europe, North America, India, and Japan (World Health Organization \u003cspan citationid=\"CR97\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). This issue is more prevalent in areas near rivers, lakes, wetlands, coastal regions, or places previously affected by floods (Omebeyinje et al. \u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Mold-affected apartments have been documented in both developed and developing countries, urban and rural areas, and in all types of residential buildings and climate zones. Recent studies indicate that indoor moisture and mold indicators impact up to 21% of European homes (Haverinen-Shaughnessy \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Norb\u0026auml;ck et al. \u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), up to 27% of Northern European homes (Bornehag et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Gunnbj\u0026ouml;rnsd\u0026oacute;ttir et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), up to 47% of American homes (Brunekreef et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1989\u003c/span\u003e; Moseley-Braun et al. \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e1995\u003c/span\u003e; Hu et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Maier et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Slezak et al. \u003cspan citationid=\"CR84\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Girman et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Freeman et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Stark et al. \u003cspan citationid=\"CR85\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Bornehag et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Gunnbj\u0026ouml;rnsd\u0026oacute;ttir et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Sun and Sundell \u003cspan citationid=\"CR86\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), and 12\u0026ndash;78% of homes in New Zealand (Howden-Chapman et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Ingham et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). In urban, suburban, and rural China, up to 12% of residential buildings have indoor mold, and up to 55% of homes are affected by window condensation (Liu et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Weir \u003cspan citationid=\"CR95\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Cai et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). A global study in both high-income and low-income countries revealed that up to 47% of homes reported the presence of indoor dampness or mold (Li et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Although there are limited studies in tropical regions, a recent survey in southern India found that 50% of homes had moisture problems (Cai et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). A study in northern Thailand reported indoor mold in 7.1% of homes and water leakage in 28.2% of homes, occurring in both the \"dry\" and \"rainy\" seasons (Weinmayr et al. \u003cspan citationid=\"CR94\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Despite improvements in building standards in developed countries (Zock et al. \u003cspan citationid=\"CR100\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Dewsbury et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2016a\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003eb\u003c/span\u003e; Prapamontol et al. \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) and an increased understanding of key risk factors for mold growth, mold-affected buildings remain a persistent and frequent problem worldwide. The presence of mold in closed residential spaces is the direct outcome of several contributing factors, including poor construction, inadequate maintenance, improper use of space, insufficient heating, and poor ventilation (Keall et al. \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Kembel et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Fisk \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Telfar-Barnard et al. \u003cspan citationid=\"CR87\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Sharpe et al. \u003cspan citationid=\"CR81\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Indoor mold growth is directly linked to the availability of sufficient moisture. Prolonged exposure to moisture within a building can significantly impact insulation, leading to increased energy consumption (Antova et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), reduced lifespan of building materials, and considerable repair and maintenance costs (Richardson \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; PricewaterhouseCoopers (PWC) \u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Alencastro et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). It is widely acknowledged that dampness and mold in living spaces have detrimental effects on the health of occupants (Cox-Ganser \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Various studies have indicated that moisture and visible mold inside buildings can lead to adverse health effects, particularly focusing on asthma, allergic reactions, respiratory infections, and respiratory symptoms. However, research on rare clinical conditions resulting from mold exposure remains relatively underexplored (Fisk et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Mendell et al. \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Cox‐Ganser 2015; Major and Boese \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The most effective measure to mitigate moisture and mold in indoor environments involves the limitation of liquid and vapor moisture within building materials (Adams et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), across the building, or within individual apartments (Mendell et al. \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Understanding the multiple causes of excessive moisture and taking preventive measures is crucial to mitigating the risk of exposure to mold, moisture, and mold-related indoor contaminants.\u003c/p\u003e \u003cp\u003ePrevious international research has identified eight key categories as risk factors for indoor mold, encompassing climate, housing conditions, socioeconomic factors, construction characteristics, tenant behavior, location, building maintenance, and urbanization (World Health Organization \u003cspan citationid=\"CR97\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Keall et al. \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Fisk \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The most common risk factors for mold growth include living conditions and construction characteristics of the building (Coulburn and Miller \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The air quality in schools can be more of a concern compared to other types of buildings due to higher population density, inadequate ventilation, and poor maintenance (Pegas et al. \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Poor indoor air quality can lead to health issues and increased absenteeism among children, who are more vulnerable to environmental hazards (Godoi et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Pegas et al. \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). It is important to collect data on bacteria and fungi in the air to protect students from potential health risks (Salin et al. \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Music schools, in particular, may have poor air quality and insufficient space, which can increase the risk of negative health effects. There is also concern about mycotoxin-producing fungi in damp indoor spaces, such as schools, which could have harmful effects on health. Research is needed to understand the health effects of indoor mycotoxins on sensitive populations. A significant number of children attend music schools, which may have microclimatic conditions that are not suitable and are used by a large number of people in a confined space. There are limited studies that examine the dispersion of microorganisms during playing and singing. Existing data primarily focus on measuring dispersion with individual instruments and modeling the dispersion of potentially infectious droplets and aerosols (Zayas et al. \u003cspan citationid=\"CR99\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Bourouiba et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Research has shown that singing can contribute to the spread of tuberculosis, as the percentage of droplets emitted into the air during singing is significantly higher than during normal conversation and is comparable to that released by coughing (Johnson et al. \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Consequently, music schools with poor indoor air quality may pose an increased risk of negative health effects. Fungal metabolites (mycotoxins) can be harmful to human and animal health and are commonly associated with mold-contaminated food. Some of the most well- known mycotoxins are aflatoxins, ochratoxin A, fumonisins, zearalenone, trichothecenes, sterigmatocystin and gliotoxin (Khan et al. \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). In addition, molds and fungi can also produce volatile organic compounds (VOCs) during their metabolism (Bennett and Inamdar \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). These compounds include various alcohols, ketones, aldehydes, esters, terpenes and others. These VOCs can contribute to the musty odor indoors and affect air quality. Concern has been raised about exposure to mycotoxin-producing fungi in enclosed spaces, such as damp apartments, offices, and schools. Although most mycotoxins that contaminate food and feed are rarely found indoors, the toxicological properties of indoor mycotoxins could have negative health effects on sensitive populations. The genera of fungi \u003cem\u003ePenicillium\u003c/em\u003e and \u003cem\u003eAspergillus\u003c/em\u003e are the primary contaminants of food and animal feed and are the dominant indoor species in moist areas. Mold enters the body through the nose via the olfactory neurons, which directly communicate with the brain. Mycotoxins induce toxicological effects similar to those associated with brain disorders such as oxidative stress and inflammation. Even a small amount of mold growth in the air conditioners and their ducts or the panels inside the buildings and even the cars cause the occupants to be chronically exposed to and constantly inhaling spores and mycotoxins, which causes illness (Ehsanifar et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Further research is needed on the health effects of mycotoxins from these indoor species, as well as the mycotoxins of \u003cem\u003eStachybotrys\u003c/em\u003e and \u003cem\u003eChaetomium\u003c/em\u003e mushrooms, due to potential long-term chronic exposure (Jarvis and Miller \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). \u003cem\u003eAspergillus, Penicillium, Fusarium, S. Chartarum\u003c/em\u003e (also known as \u003cem\u003eS. Atra\u003c/em\u003e), \u003cem\u003ePaecilomyces\u003c/em\u003e, and \u003cem\u003eTrichoderma\u003c/em\u003e species are important toxigenic fungi from a public health perspective. These fungi are linked to harmful effects on the health of humans and animals, causing specific organ damage and diseases that are typically neither allergic nor infectious (Li et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). A recent investigation by the Australian government into illnesses related to biotoxins found that tenants living in mold-infested apartments experienced negative health impacts (Hyv\u0026ouml;nen et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). This drew attention to the dangers of poorly researched airborne mycotoxins.\u003c/p\u003e \u003cp\u003eThis study is one of the first to investigate airborne bacteria and fungi in connection with possible mycotoxin exposure in children in Croatia. The focus of this study was to investigate the levels of bacteria and fungi present in the air at a music school that has been treated for moisture, and to explore any potential correlation between the airborne fungi and mycotoxins identified in the urine of a child with autism spectrum disorder (ASD) who regularly attends the school. Mold spores and mycotoxins can trigger or worsen respiratory conditions such as asthma and allergies in children with autism, exacerbating cognitive and behavioral symptoms associated with autism and compromise the immune system, making children more susceptible to infections and inflammation (De Santis et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Ratnaseelan et al. \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Serkan et al. \u003cspan citationid=\"CR80\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Recent epidemiologic findings have shown a significant association between ASD and mycotoxin exposure; it reads as 1 in 36 children are affected by ASD that is caused/linked by mycotoxin exposure (Shaw et al. \u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Maenner et al. \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The specific objectives of this investigation were as follows: 1. To quantify the concentrations of bacteria and fungi in the air that may have potential implications for human health; 2. To identify the types of fungi present; 3. To assess the influence of external concentrations of bacteria and fungi on indoor air quality; 4. To determine whether the mycotoxins identified in the child's with ASD urine can be associated with airborne fungi.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eIn a Music school in Zagreb, air samples were collected as part of a microbiological study. The school is used by 20 students on a daily basis and is located in a space originally designed as an atomic shelter, without external openings. Within this space, an air dehumidifier operates continuously, and a AC (air conditioner) device was turned off during the measurement. Although there was a distinct moldy smell in the room, no visible mold was observed. The microclimatic conditions encountered are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMicroclimatic conditions at the sampling locations, as well as the measured concentrations of CO\u003csub\u003e2\u003c/sub\u003e and PM particles\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAir temperature (\u0026deg;C)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRelative Humidity (%Rh)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNumber of people present\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(ppm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003epartices (PM)\u0026thinsp;\u0026ge;\u0026thinsp;1\u0026micro;m\u003c/p\u003e \u003cp\u003e(Counts/m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eentrance area of atomic shelter\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e698\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e982686\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emiddle area of atomic shelter\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e702\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1537103\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003erear area of atomic shelter\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e710\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1225795\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eoutside air\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e578\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e58657\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe microbiological studies involved assessing the total number of mesophilic bacteria and molds. Air samples were collected using the SAS-360 DUO air sampler. The tested air volumes were 2 x 100 and 2 x 200 liters for each measurement location, and the sampling rate was\u003c/p\u003e \u003cp\u003e360 l/min. After sampling the air on nutrient media (International Organization for Standardization (ISO) \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2011a\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003eb\u003c/span\u003e), the media were incubated at a specific temperature for a certain duration. Indoor air sampling was performed using a SAS 360 DUO sampler using the active SAS method on TSA (Tripton soy agar, LOT: 230718/21.10.2024) and DG18 agar (Dicloran 18% glycerol agar, LOT:180918/16.12.2024) (International Organization for Standardization (ISO) \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2011a\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003eb\u003c/span\u003e). Additionally, outdoor air sampling was conducted in accordance with the standards ISO 16000-1 and ISO 16000-19 (International Organization for Standardization (ISO) \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe evaluation of indoor air microbiological testing involves comparing microbiological indicators of outdoor and indoor air (Yassin and Almouqatea \u003cspan citationid=\"CR98\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). According to the Portuguese standard stated in Portugese standard n\u0026ordm; 353-A/2013 (Minist\u0026eacute;rios do Ambiente Ordenamento do Territ\u0026oacute;rio e Energia da Sa\u0026uacute;de e da Solidariedad Emprego e Seguran\u0026ccedil;a Social \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), a concentration of the total number of bacteria in the indoor air must be lower than the outdoor concentration\u0026thinsp;+\u0026thinsp;350 CFU/m\u003csup\u003e3\u003c/sup\u003e, and the mold concentration of the indoor air must be lower than that of the outdoor air (International Organization for Standardization (ISO) \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). After sampling, nutrient media, TSA, and DG 18 are incubated. Nutrient media for determining the total number of bacteria (on TSA) are incubated at (37\u0026thinsp;\u0026plusmn;\u0026thinsp;3) \u0026deg;C for 2 days. If there's no colony growth, incubation can be extended up to 7 days. Nutrient media for determining the total number of molds are incubated for 7 days at (25\u0026thinsp;\u0026plusmn;\u0026thinsp;3) \u0026deg;C. DG 18 agar can be incubated for 10 days if further mold identification is necessary. The average number of bacteria and fungi is calculated as colony-forming units in 1 m\u003csup\u003e3\u003c/sup\u003e (CFU/m\u003csup\u003e3\u003c/sup\u003e). The number of microorganisms counted on the surface of the nutrient medium must be corrected for the possibility of a statistical error that occurs due to the probability of the passage of different types of particles through the holes in the aspiration head of the instrument. The conversion formula is taken from the SAS Device User's Guide. The probable number (Pr) from the table is then used to calculate (CFU) per cubic meter of air sampled. Example of result calculation (Eq.\u0026nbsp;1):\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:X=\\frac{{P}_{r}\\times\\:1000}{V}\\)\u003c/span\u003e \u003c/span\u003e [1]\u003c/p\u003e \u003cp\u003ewhere is\u003c/p\u003e \u003cp\u003e \u003cem\u003eV\u003c/em\u003e - volume of sampled air\u003c/p\u003e \u003cp\u003e \u003cem\u003eP\u003c/em\u003e \u003csub\u003e \u003cem\u003er\u003c/em\u003e \u003c/sub\u003e - possible number of CFU obtained from the correction table\u003c/p\u003e \u003cp\u003e \u003cem\u003eX\u003c/em\u003e - no. CFU per m\u003csup\u003e3\u003c/sup\u003e of air\u003c/p\u003e \u003cp\u003eAccording to the ISO 16000-17 standard (International Organization for Standardization (ISO) \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), the number of mold colonies counted on the nutrient medium surface does not need to be adjusted. The mold concentration per cubic meter of air is expressed by calculating the number of colonies for each identified species individually. Unidentified species are categorized as \"others\". The total mold colony count is the sum of identified mold species and \"others\". The total mold count (CFU) per cubic meter is calculated according to the equation (Eq.\u0026nbsp;2):\u003c/p\u003e \u003cp\u003eC\u003csub\u003ei\u003c/sub\u003e = n\u003csub\u003eCFU\u003c/sub\u003e / V\u003csub\u003ei\u003c/sub\u003e [2]\u003c/p\u003e \u003cp\u003ewhere is\u003c/p\u003e \u003cp\u003e \u003cem\u003eV\u003c/em\u003e \u003csub\u003e \u003cem\u003ei\u003c/em\u003e \u003c/sub\u003e - volume of sampled air\u003c/p\u003e \u003cp\u003e \u003cem\u003en\u003c/em\u003e \u003csub\u003e \u003cem\u003eCFU\u003c/em\u003e \u003c/sub\u003e- number of CFU\u003c/p\u003e \u003cp\u003e \u003cem\u003eC\u003c/em\u003e \u003csub\u003e \u003cem\u003ei\u003c/em\u003e \u003c/sub\u003e - no. CFU per m\u003csup\u003e3\u003c/sup\u003e of air\u003c/p\u003e \u003cp\u003eAs per the EN 13098 standard (European Standards \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), the total number of microorganisms in the air is measured as the number of colonies per cubic meter of air (CFU/m\u003csup\u003e3\u003c/sup\u003e). The main fungal isolates were identified using the Bruker MALDI Biotyper method. Parameters like relative humidity, temperature, and the number of people in the building were recorded during sampling. The MycoTOX Child Profile, a modern urine-based test, was used to accurately assess the levels of 11 different mycotoxins, including aflatoxin M1, ochratoxin A, gliotoxin, mycophenolic acid, and zearalenone. This profile utilizes liquid chromatography technology to detect free (unconjugated) mycotoxins even at low levels (Bennett and Klich \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Janik et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cp\u003eThe environmental survey was meticulously conducted during the spring season to evaluate and characterize the indoor air quality of the specified enclosed space. Throughout the assessment, the outdoor air temperature was measured at approximately 12.7\u0026deg;C, providing a baseline for comparison. In contrast, the indoor temperature within the enclosed environment fluctuated between 15.2\u0026deg;C and 15.7\u0026deg;C, indicating a regulated climate controlled by the building\u0026rsquo;s heating, ventilation, and air conditioning systems. Regarding relative humidity, the indoor levels exhibited variability between 40.7% and 41.2%. This variance was influenced by specific locations where air samples were collected, highlighting the spatial differences in humidity distribution within the space. For comparison, the outdoor relative humidity was found to be 39.1%, which serves as a reference point for evaluating the effectiveness of the indoor environmental controls. It is noteworthy that the enclosed area under investigation was equipped with both a dehumidifier and an air conditioning system. These systems are designed to manage and regulate indoor humidity levels, and their presence could significantly impact the indoor humidity measurements obtained during the survey. Additionally, the findings from the microbiological analysis, which provide critical insights into the indoor air quality, have been visually represented in Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. These figures not only provide visual representation of the data but are also integral for a comprehensive understanding of the types and concentrations of microorganisms present, as well as the potential contaminants that may affect the overall indoor air quality of the environment surveyed.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe investigation uncovered that the back area of the space was significantly tainted with bacteriological contamination, indicating the presence of various harmful bacteria that could pose health risks. This area\u0026rsquo;s conditions likely favored the proliferation of microbes, which can thrive in damp or poorly ventilated environments. In stark contrast, the entrance area revealed a troubling abundance of mold, which suggests that factors such as humidity, inadequate lighting, or insufficient airflow may have contributed to its growth. To accurately identify the specific types of mold and yeast present, researchers utilized the advanced Bruker MALDI Biotyper method, a sophisticated technique renowned for its ability to precisely identify microorganisms based on their unique protein profiles. Through this analysis, a remarkable array of microbial species was discovered, totaling 55 distinct types of mold alongside one type of yeast. Among the identified species was \u003cem\u003eAspergillus flavus\u003c/em\u003e, notorious for its potential to produce toxic aflatoxins that can contaminate food supplies. \u003cem\u003ePenicillium verrucosum\u003c/em\u003e, which can also generate harmful mycotoxins, was likewise detected. The presence of \u003cem\u003eAspergillus fumigatus\u003c/em\u003e was noted, a mold well-known for its association with respiratory ailments, particularly in individuals with weakened immune systems. The catch-all category of \u003cem\u003ePenicillium spp.\u003c/em\u003e pointed to several mold types typically found in indoor settings. Additionally, researchers found \u003cem\u003eAlternaria alternata\u003c/em\u003e, a common allergenic mold that can trigger allergic reactions and asthma in sensitive individuals. Notably, they also isolated \u003cem\u003eCandida albicans\u003c/em\u003e, a type of yeast that can lead to infections, particularly in those with compromised immune systems. Comprehensive details about these identified microorganisms, including their potential risks and impact on health, can be found in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTypes of isolated molds in various locations within the investigated area.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eentrance area of atomic shelter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003emiddle area of atomic shelter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003erear area of atomic shelter\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eAspergillus flavus\u003c/em\u003e (11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eAlternaria alternata\u003c/em\u003e (5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ePenicillium spp\u003c/em\u003e (7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePenicillium spp\u003c/em\u003e (6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePenicillium verrucosum\u003c/em\u003e (12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ePenicillium verrucosum\u003c/em\u003e (12)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eAspergillus fumigatus\u003c/em\u003e (29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eAspergillus fumigatus\u003c/em\u003e (13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eAspergillus fumigatus\u003c/em\u003e (13)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eCandida albicans\u003c/em\u003e (3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eAspergillus flavus\u003c/em\u003e (10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eAspergillus flavus\u003c/em\u003e (10)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eAlternaria alternata\u003c/em\u003e (5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAccording to the Portuguese standard stated in Portugese standard n\u0026ordm; 353-A/2013 (Minist\u0026eacute;rios do Ambiente Ordenamento do Territ\u0026oacute;rio e Energia da Sa\u0026uacute;de e da Solidariedad Emprego e Seguran\u0026ccedil;a Social \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), a thorough assessment of indoor air quality was conducted, focusing on the total number of bacteria and molds present. The results indicated that the measured levels of both microorganisms remained well within the specified reference values, indicating a safe indoor environment. The concentration of the total number of bacteria in the indoor air must be lower than the outdoor concentration\u0026thinsp;+\u0026thinsp;350 CFU/m\u003csup\u003e3\u003c/sup\u003e, and the mold concentration of the indoor air must be lower than that of the outdoor air (International Organization for Standardization (ISO) \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). This ensures that indoor spaces maintain a healthy atmosphere, effectively minimizing the risk of airborne bacterial proliferation. Similarly, regarding mold concentrations, it is essential that the levels inside the premises do not exceed those detected in the outdoor environment. This guideline serves to prevent potential health issues associated with mold exposure. Additionally, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e provides a comprehensive overview of the elevated levels of mycotoxins that were isolated from the urine samples of the child with ASD in question. In one study, the comparison of urine and serum ochratoxin A levels in 52 children with ASD with healthy children was significant (De Santis et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Also, in a cross-sectional study, the different mycotoxins levels (fumonisin B1, ochratoxin A, and aflatoxin M1) were notably higher in the urine and serum of 172 children with ASD compared to 61 healthy individuals (De Santis et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). These findings raise important considerations about possible exposure to harmful substances, warranting further investigation and attention to the child's environmental conditions. The presence of mycotoxins in urine is often a key indicator of exposure, making it crucial to monitor and address any potential sources in the child's surroundings.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe quality of air within educational institutions, such as schools and kindergartens, is an area of significant concern and interest among researchers, given the vital role these environments play in the development and health of children. Children spend a considerable portion of their day in these settings, making it crucial to ensure that the air they breathe is free from harmful pollutants. Numerous research studies have been conducted to investigate various aspects of air quality, with a particular emphasis on microbiological pollution. This includes examining the types and concentrations of microorganisms, such as bacteria and fungi, that can adversely affect health and contribute to allergic reactions or respiratory issues. These studies have produced a wealth of valuable data that has been meticulously compiled and is presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. This table offers detailed and quantitative information regarding the levels of bacteria and fungi present in the airborne environment of educational facilities. It integrates findings from a diverse array of literature, encompassing various methodologies and conditions under which air samples were collected, thereby providing a comprehensive overview of the microbiological landscape in schools and kindergartens. The results underscore the necessity of continuous monitoring and improvement of air quality in these institutions, emphasizing their critical role in safeguarding the health and well-being of young learners and creating a conducive learning environment.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInformation on the quantity of bacteria and fungi present in the air of school institutions (literature sources)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSampling site\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003enumber of bacteria (CFU/m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003enumber of fungi\u003c/p\u003e \u003cp\u003e(CFU/m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ereferences\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eschool corridors\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7700\u0026ndash;8200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e(Karwowska \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2003\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003elaboratories\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1600\u0026ndash;2000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e160\u0026ndash;780\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eother rooms inside the school\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u0026ndash;1000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Karbowska-Berent et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2011\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003electure rooms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e493\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Filipiak et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2004\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eclassrooms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75\u0026thinsp;\u0026minus;\u0026thinsp;56 000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23-1400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Enitan et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2017\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eschool premises\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0-550\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Meklin et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2002\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCroatia currently lacks standards and regulations for microbiological contaminant levels in indoor air. According to the Portuguese standard (Minist\u0026eacute;rios do Ambiente Ordenamento do Territ\u0026oacute;rio e Energia da Sa\u0026uacute;de e da Solidariedad Emprego e Seguran\u0026ccedil;a Social \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), the total number of bacteria and molds in indoor air should not exceed specific reference values. Despite the levels in our research being below these reference values, we found yeasts and molds that could negatively impact health, particularly for individuals with compromised immune systems (Salin et al. \u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Tuuminen et al. \u003cspan citationid=\"CR89\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Scientific evidence suggests that exposure to moisture-related microbes and decay products from moisture-damaged building materials can lead to a range of health issues known as moisture and mold hypersensitivity syndrome (DMHS)(Valtonen \u003cspan citationid=\"CR92\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Vaali et al. \u003cspan citationid=\"CR91\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Prolonged exposure to these microbes and decay products may result in symptoms such as fatigue, neurological, gastrointestinal, musculoskeletal problems, and respiratory issues (Hyv\u0026ouml;nen et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Vornanen-Winqvist et al. \u003cspan citationid=\"CR93\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Hyvonen et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Vaali et al. \u003cspan citationid=\"CR91\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Diagnosing DMHS currently relies on clinical observations and patient data, as a specific biomarker has not been developed. Continuous or cumulative exposure to moisture-related microbes and decay products can worsen symptoms and lead to irreversible multiorgan DMHS (Hyv\u0026ouml;nen et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Vaali et al. \u003cspan citationid=\"CR91\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Mycotoxins may also be effective in ASD. A study on 172 children with ASD with 61 controls showed significant differences comparing antibodies to mycotoxins between the 2 groups, and the ASD group indicated higher serum antibodies to mycotoxins (De Santis et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Research findings from the Tufts University School of Medicine suggested that mycotoxins cause ASD. Mycotoxins, toxic byproducts of mold, can cause mycotoxicosis upon entering the body. To assess the risk of mold exposure in enclosed spaces, it is crucial to apply knowledge about agriculturally important toxins and conduct further research to understand the relationship between mycotoxin exposure and health issues (Cole and Cox \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Cole et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). Research is also needed to comprehend how various factors influence the outcomes of mold exposure. Additionally, it is important to note that people genetically predisposed to allergies and asthma may be more sensitive to mold and mildew spores, potentially contributing to upper respiratory tract problems, especially in children (Bornehag et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). While assessing the role of mold exposure in causing disease symptoms without direct measurement through biomarkers is challenging, there is a likelihood that toxins from building-associated fungi play a role in causing health issues. Further studies are required to understand the impact of low molecular weight toxins on lung biology (Miller et al. \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2003\u003c/span\u003e) and to identify the types and amounts of toxin metabolites present in residential buildings.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eThe findings of the study reveal that the levels of airborne fungi in the music classroom exhibit a consistent distribution pattern. This pattern largely stems from the shared air-conditioning and ventilation system that connects the indoor environment to the outside atmosphere. The presence of a limited number of isolated mold species, which manifest at lower concentrations compared to outdoor levels, is largely due to the proactive use of air dehumidifiers within the classroom. These dehumidifiers help to minimize moisture, thereby reducing mold growth. However, some of the isolated molds possess the ability to produce mycotoxins - toxic compounds that are recognized for their harmful effects on both humans and animals. When these mycotoxins are released into the air, they can contribute to a range of detrimental health effects due to their toxic nature. The synergistic inhalation of these fungal byproducts can lead to various health problems, including respiratory irritation, general toxicity, and even more serious conditions such as teratogenicity (developmental issues), carcinogenicity (cancer risk), and immunosuppression (a weakened immune response). This situation poses a particularly significant risk for atopic children, who are more vulnerable to allergens and irritants, including fungal spores. In environments where mycotoxin-producing fungi are present, these children may experience exacerbated symptoms and complications that contribute to overall indoor air pollution. The potential link between mold exposure and ASD represents a significant shift in our understanding of this complex disorder. While more research is needed to fully elucidate the connection, the emerging evidence suggests that environmental factors, including mold exposure, may play a more significant role in ASD symptoms than previously thought.Given the potential health hazards associated with mycotoxins in enclosed spaces, needs further research. Given the potential health hazards associated with mycotoxins in enclosed spaces, there is an urgent call for further research. This research is essential to deepen our understanding of the dynamics of mycotoxins in indoor environments and to assess their potential adverse effects on human health, particularly among sensitive populations such as children.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eACKNOWLEDGEMENT\u003c/p\u003e\n\u003cp\u003eThis activity was carried out within the \u0026ldquo;Food Safety and Quality Center\u0026rdquo; (KK.01.1.1.02.0004) project funded by the European Regional Development Fund and was performed using the facilities and equipment funded within the European Regional Development Fund project KK.01.1.1.02.0007 \u0026quot;Research and Education Centre of Environmental Health and Radiation Protection \u0026ndash; Reconstruction and Expansion of the Institute for Medical Research and Occupational Health\u0026quot;, and funded by the European Union \u0026ndash; Next Generation EU (Program Contract of 8 December 2023, Class: 643-02/23-01/00016, Reg. no. 533-03-23-0006)-EnvironPollutHealth.\u003c/p\u003e\n\u003cp\u003eAuthor contributions:\u003c/p\u003e\n\u003cp\u003eIM \u0026ndash; Writing \u0026ndash; original draft, Investigation, Conceptualization, Data curation, Formal analysis, Methodology, Validation\u003c/p\u003e\n\u003cp\u003eAK \u0026ndash; Writing \u0026ndash; review and editing, Supervision\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEKV \u0026ndash; Writing \u0026ndash; review and editing, Supervision\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRG \u0026ndash; Writing \u0026ndash; review and editing, Visualization, Conceptualization\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAdams RI, Bhangar S, Dannemiller KC, et al (2016) Ten questions concerning the microbiomes of buildings. 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Adv Appl Microbiol 55:1\u0026ndash;30. https://doi.org/10.1016/S0065-2164(04)55001-3\u003c/li\u003e\n\u003cli\u003eCoulburn L, Miller W (2022) Prevalence, Risk Factors and Impacts Related to Mould-Affected Housing: An Australian Integrative Review. Int J Environ Res Public Health 19:1854. https://doi.org/10.3390/ijerph19031854\u003c/li\u003e\n\u003cli\u003eCox‐Ganser JM (2015) Indoor dampness and mould health effects \u0026ndash; ongoing questions on microbial exposures and allergic versus nonallergic mechanisms. Clin Exp Allergy 45:1478\u0026ndash;1482. https://doi.org/10.1111/cea.12601\u003c/li\u003e\n\u003cli\u003eDaisey JM, Angell WJ, Apte MG (2003) Indoor air quality, ventilation and health symptoms in schools: an analysis of existing information. Indoor Air 13:53\u0026ndash;64. https://doi.org/10.1034/j.1600-0668.2003.00153.x\u003c/li\u003e\n\u003cli\u003eDe Santis B, Brera C, Mezzelani A, et al (2019) Role of mycotoxins in the pathobiology of autism: A first evidence. 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Build Environ 86:70\u0026ndash;80. https://doi.org/10.1016/j.buildenv.2014.12.024\u003c/li\u003e\n\u003cli\u003eFisk WJ, Eliseeva EA, Mendell MJ (2010) Association of residential dampness and mold with respiratory tract infections and bronchitis: a meta-analysis. Environ Heal 9:72. https://doi.org/10.1186/1476-069X-9-72\u003c/li\u003e\n\u003cli\u003eFreeman NCG, Schneider D, McGarvey P (2003) Household exposure factors, asthma, and school absenteeism in a predominantly Hispanic community. J Expo Sci Environ Epidemiol 13:169\u0026ndash;176. https://doi.org/10.1038/sj.jea.7500266\u003c/li\u003e\n\u003cli\u003eGirman JR, Baker BJ, Burton LE (2002) Prevalence of Potential Sources of Indoor Air Pollution in U. S. Office Buildings. In: Proceedings of the 9th International Conference on Indoor Air Quality and Climate. Monterey, California, pp 438\u0026ndash;443\u003c/li\u003e\n\u003cli\u003eGodoi RHM, Avigo D, Campos VP, et al (2009) Indoor Air Quality Assessment of Elementary Schools in Curitiba, Brazil. Water, Air, Soil Pollut Focus 9:171\u0026ndash;177. https://doi.org/10.1007/s11267-009-9220-3\u003c/li\u003e\n\u003cli\u003eGunnbj\u0026ouml;rnsd\u0026oacute;ttir MI, Franklin KA, Norb\u0026auml;ck D, et al (2006) Prevalence and incidence of respiratory symptoms in relation to indoor dampness: the RHINE study. Thorax 61:221\u0026ndash;225. https://doi.org/10.1136/thx.2005.057430\u003c/li\u003e\n\u003cli\u003eHagerhed-Engman L, Bornehag C-G, Sundell J, A berg N (2006) Day‐care attendance and increased risk for respiratory and allergic symptoms in.pdf. Allergy 61:447\u0026ndash;453. https://doi.org/10.1111/j.1398-9995.2006.01031\u003c/li\u003e\n\u003cli\u003eHaverinen-Shaughnessy U (2012) Prevalence of dampness and mold in European housing stock. 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Saf Health Work 11:173\u0026ndash;177. https://doi.org/10.1016/j.shaw.2020.01.003\u003c/li\u003e\n\u003cli\u003eHyv\u0026ouml;nen S, Poussa T, Lohi J, Tuuminen T (2021) High prevalence of neurological sequelae and multiple chemical sensitivity among occupants of a Finnish police station damaged by dampness microbiota. Arch Environ Occup Health 76:145\u0026ndash;151. https://doi.org/10.1080/19338244.2020.1781034\u003c/li\u003e\n\u003cli\u003eHyvonen SM, Lohi JJ, Rasanen LA, et al (2020) Association of toxic indoor air with multi-organ symptoms in pupils attending a moisture-damaged school in Finland. Am J Clin Exp Immunol 9:101\u0026ndash;113\u003c/li\u003e\n\u003cli\u003eIngham T, Keall M, Jones B, et al (2019) Damp mouldy housing and early childhood hospital admissions for acute respiratory infection: a case control study. Thorax 74:849\u0026ndash;857. https://doi.org/10.1136/thoraxjnl-2018-212979\u003c/li\u003e\n\u003cli\u003eInternational Organization for Standardization (ISO) (2011a) ISO 16000-18:2011 Indoor air Part 18: Detection and enumeration of moulds \u0026mdash; Sampling by impaction\u003c/li\u003e\n\u003cli\u003eInternational Organization for Standardization (ISO) (2011b) ISO 16000-18:2011/Cor 1:2011 Indoor air \u0026mdash; Part 18: Detection and enumeration of moulds \u0026mdash; Sampling by impaction Technical Corrigendum 1\u003c/li\u003e\n\u003cli\u003eInternational Organization for Standardization (ISO) (2008) ISO 16000-17:2008 - Detection and enumeration of moulds \u0026mdash; Culture-based method\u003c/li\u003e\n\u003cli\u003eInternational Organization for Standardization (ISO) (2009) ISO 16000-17:2008/Cor 1:2009 Indoor air \u0026mdash; Part 17: Detection and enumeration of moulds \u0026mdash; Culture-based method Technical Corrigendum 1\u003c/li\u003e\n\u003cli\u003eInternational Organization for Standardization (ISO) (2004) ISO 16000-1:2004 Indoor air Part 1: General aspects of sampling strategy\u003c/li\u003e\n\u003cli\u003eInternational Organization for Standardization (ISO) (2012) ISO 16000-19:2012 Indoor air Part 19: Sampling strategy for moulds\u003c/li\u003e\n\u003cli\u003eJanik E, Niemcewicz M, Ceremuga M, et al (2020) Molecular Aspects of Mycotoxins\u0026mdash;A Serious Problem for Human Health. 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Environ Int 141:105781. https://doi.org/10.1016/j.envint.2020.105781\u003c/li\u003e\n\u003cli\u003eWeinmayr G, Gehring U, Genuneit J, et al (2013) Dampness and moulds in relation to respiratory and allergic symptoms in children: results from Phase Two of the International Study of Asthma and Allergies in Childhood ( \u0026lt;scp\u0026gt;ISAAC\u0026lt;/scp\u0026gt; Phase Two). Clin Exp Allergy 43:762\u0026ndash;774. https://doi.org/10.1111/cea.12107\u003c/li\u003e\n\u003cli\u003eWeir J (2019) One in five homes damp. https://www.stats.govt.nz/news/one-in-five-homes-damp/. Accessed 10 Dec 2024\u003c/li\u003e\n\u003cli\u003eWorld Health Organization (2010) WHO guidelines for indoor air quality: selected pollutants\u003c/li\u003e\n\u003cli\u003eWorld Health Organization (2009) WHO guidelines for indoor air quality: dampness and mould\u003c/li\u003e\n\u003cli\u003eYassin MF, Almouqatea S (2010) Assessment of airborne bacteria and fungi in an indoor and outdoor environment. Int J Environ Sci Technol 7:535\u0026ndash;544. https://doi.org/10.1007/BF03326162\u003c/li\u003e\n\u003cli\u003eZayas G, Chiang MC, Wong E, et al (2012) Cough aerosol in healthy participants: fundamental knowledge to optimize droplet-spread infectious respiratory disease management. BMC Pulm Med 12:11. https://doi.org/10.1186/1471-2466-12-11\u003c/li\u003e\n\u003cli\u003eZock J-P, Jarvis D, Luczynska C, et al (2002) Housing characteristics, reported mold exposure, and asthma in the European Community Respiratory Health Survey. J Allergy Clin Immunol 110:285\u0026ndash;292. https://doi.org/10.1067/mai.2002.126383\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"poor sanity conditions, indoor spaces, children's health, mesophilic bacteria, mold","lastPublishedDoi":"10.21203/rs.3.rs-5632354/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5632354/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eClean air is essential for human well-being, especially indoors. Indoor air quality has a significant impact on human health and there is concern about the health effects of exposure to airborne bacteria and fungi. The World Health Organization has warned of adverse health effects associated with building moisture and biological agents. Mold growth due to indoor moisture affects a significant percentage of buildings worldwide, leading to increased health risks, especially for children. It is crucial to work on implementing effective solutions to create healthier indoor environments for children worldwide.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis study investigates the adverse health effects of total indoor air bacteria and molds and potential exposure to mycotoxins, which are products of airborne molds, on school-aged children. The study was conducted in the Music School in Zagreb, where children spend a few hours a day in a space originally designed as a nuclear shelter, without external openings, and the findings strongly suggest that the airborne mold levels in the music classroom are consistently distributed due to the shared air conditioning and ventilation system shared with the outdoor environment.The presence of a few isolated molds, with lower concentrations than outdoors, may be attributable to the regular use of air dehumidifiers. Low concentrations of airborne mold may pose a health risk for atopic children who are particularly susceptible to fungal spores, especially in environments contaminated with mycotoxin-producing fungi, further contribute to indoor air pollution.\u003c/p\u003e","manuscriptTitle":"Mycotoxins Present in the Indoor Air of a Music School Repurposed from an Atomic Shelter","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-25 15:39:22","doi":"10.21203/rs.3.rs-5632354/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"591b9e9b-90c6-4d9a-971c-41dbd66e3183","owner":[],"postedDate":"December 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-02-25T12:09:00+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-25 15:39:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5632354","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5632354","identity":"rs-5632354","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}