Air quality is a critical aspect of indoor environments, influencing the health and well-being of individuals who spend significant time indoors. Libraries, as spaces designed for learning, research, and leisure, house a vast collection of books and other materials that are essential for education and intellectual growth. The quality of air within library settings can have a direct impact on the preservation of these materials, as well as on the health and comfort of library patrons and staff.

Significance of Study: Understanding the relationship between air quality and library books and materials is crucial for ensuring the longevity and preservation of these valuable resources. Poor air quality can lead to the deterioration of books through factors such as mold growth, pest infestation, and chemical degradation. Additionally, indoor air pollutants can pose health risks to those who frequent libraries, making it imperative to investigate and address potential issues related to air quality in these environments.

Statement of the Problem: Despite the significance of air quality in libraries, there is a gap in research on the specific impacts of indoor air quality on library books and other materials. Limited studies have been conducted to explore the potential risks posed by poor air quality to the preservation of library collections and the health of library users. Addressing this gap in knowledge is essential for developing effective strategies to maintain optimal air quality within library spaces.

Justifications: By investigating the relationship between air quality and library materials, this study aims to provide valuable insights that can inform the development of best practices for maintaining a healthy indoor environment in libraries. Implementing appropriate measures to monitor and improve air quality can help preserve valuable library collections, protect the health of library patrons and staff, and enhance the overall quality of the library experience.

Limitations of Study: This study may be limited by factors such as the specific environmental conditions of the libraries under investigation, the availability of resources for air quality monitoring, and the scope of the research methods employed. Additionally, external factors such as seasonal variations and building design can influence indoor air quality and may impact the generalizability of the study findings.

Scope of Study: This study will focus on assessing the impact of indoor air quality on the preservation of library books and materials, as well as the potential health implications for library users. The research will involve monitoring air quality parameters such as temperature, humidity, particulate matter, and volatile organic compounds in selected library settings.

Research Questions

1. What are the key factors contributing to indoor air quality in library environments?
2. How does indoor air quality impact the preservation of library books and materials?
3. What are the potential health risks associated with poor air quality in libraries?

Aim and Objectives of Study: The aim of this study is to investigate the relationship between air quality and library books and materials, with the following objectives:

• To assess the current indoor air quality in selected library settings.
• To evaluate the impact of indoor air quality on the preservation of library collections.
• To identify potential health risks associated with poor air quality in libraries.

Theoretical Framework of Quality in Library Environments

Indoor air quality (IAQ) in library environments is influenced by various factors, including building design, ventilation systems, occupancy, and sources of indoor pollutants. Understanding the theoretical framework governing IAQ in libraries involves integrating principles from several disciplines, including environmental science, building engineering, and public health. The theoretical framework can be structured around the following key concepts:

Building design features, such as the layout, size, and materials used, can impact IAQ. Proper ventilation systems, including mechanical ventilation, air filtration, and natural ventilation strategies, play a crucial role in maintaining optimal IAQ levels [1]. The design and layout of Heating, Ventilation, and Air Conditioning (HVAC) systems significantly impact IAQ. Properly designed HVAC systems should provide adequate ventilation rates, filtration, and temperature and humidity control to ensure optimal air quality [2]. High-efficiency particulate air (HEPA) filters and other advanced filtration systems can effectively capture airborne pollutants, including particulate matter, allergens, and microorganisms. Regular maintenance and replacement of filters are essential to ensure their effectiveness in removing contaminants [3]. Incorporating natural ventilation strategies, such as operable windows and louvers, can enhance indoor air quality by facilitating the exchange of outdoor and indoor air. However, the effectiveness of natural ventilation depends on factors such as outdoor air pollution levels, weather conditions, and building orientation [4]. Selection of low-emission building materials, paints, adhesives, and finishes can minimize the release of volatile organic compounds (VOCs) and other harmful chemicals into the indoor environment. Green building standards, such as LEED (Leadership in Energy and Environmental Design), promote the use of low-VOC materials to improve IAQ [5]. Proper moisture management is essential for preventing mold growth and maintaining IAQ. Building design features, such as vapor barriers, waterproofing, and adequate drainage systems, help mitigate moisture infiltration and accumulation in indoor spaces, reducing the risk of mold and microbial contamination [6]. The design of library spaces should consider occupant density, furniture arrangement, and circulation patterns to optimize air distribution and ventilation effectiveness. Overcrowded or poorly ventilated areas may result in stagnant air and increased concentrations of indoor pollutants [7].

Occupant activities, such as reading, studying, and using electronic devices, can contribute to indoor air pollution through the release of particulate matter, volatile organic compounds (VOCs), and carbon dioxide (CO2). Occupant behavior, including smoking and eating habits, also influences IAQ [8]. The activities of library occupants, such as reading and studying, can affect IAQ. Handling of books, documents, and papers may release particulate matter into the air, especially in older or poorly maintained library collections. Implementing measures such as regular dusting, book cleaning, and proper storage can mitigate the release of airborne particles [9]. Occupants' use of electronic devices, including laptops, tablets, and smartphones, can contribute to indoor air pollution through the emission of electromagnetic radiation and heat. Additionally, electronic devices may release volatile organic compounds (VOCs) and other chemicals from their components and batteries, impacting IAQ [10]. Printing and photocopying activities in library spaces can generate airborne pollutants such as toner dust and ozone. Printers and photocopiers equipped with high-efficiency air filters and ozone removal systems can help reduce the emission of these pollutants into the indoor environment [11]. High occupant density in library spaces can lead to increased emissions of carbon dioxide (CO2) and body odors, impacting IAQ and occupant comfort. Proper ventilation and air circulation are essential for maintaining acceptable CO2 levels and preventing the buildup of odors [12]. Consumption of food and beverages in library spaces can introduce odors and airborne particles into the indoor environment. Implementing policies to restrict or regulate food and beverage consumption, as well as providing designated eating areas with proper ventilation, can help minimize the impact on IAQ [13]. Personal hygiene practices of occupants, such as hand washing and coughing etiquette, can influence IAQ by reducing the spread of respiratory droplets and airborne pathogens. Promoting good hygiene habits through educational campaigns and providing hand hygiene facilities can contribute to maintaining a healthy indoor environment [14].

Indoor pollutants in library environments originate from various sources, including building materials, furniture, cleaning products, and occupants' personal belongings. Particulate matter, VOCs, formaldehyde, and biological contaminants (e.g., mold, bacteria) are common indoor pollutants in libraries [15]. Particulate matter consists of tiny particles suspended in the air and can originate from various sources such as outdoor pollution, human activities, and building materials. Fine particulate matter (PM2.5) and coarse particulate matter (PM10) can penetrate indoor spaces and pose health risks, including respiratory and cardiovascular problems [16]. VOCs are organic chemicals that can easily vaporize into the air at room temperature. Sources of VOCs in libraries include building materials, furniture, cleaning products, and office equipment. Prolonged exposure to VOCs may cause irritation of the eyes, nose, and throat, as well as headaches and dizziness [17]. Formaldehyde is a colorless gas with a pungent odor that can be emitted from various sources such as plywood, carpeting, and furniture made from composite wood products. Prolonged exposure to formaldehyde may cause respiratory issues and has been classified as a carcinogen by international health organizations [18]. Biological contaminants in indoor environments include mold, bacteria, viruses, pollen, and dust mites. Libraries with inadequate ventilation or high humidity levels may experience microbial growth, leading to indoor air quality problems and potential health effects, particularly for individuals with allergies or respiratory conditions [19]. Ozone (O3) is a reactive gas that can enter indoor environments from outdoor sources or be generated indoors by photocopiers, printers, and electronic devices. Ozone exposure can cause respiratory irritation, exacerbate asthma symptoms, and reduce lung function [20]. Radon is a naturally occurring radioactive gas that can seep into buildings from the soil and rock beneath them. Libraries located in regions with high radon levels may be at risk of indoor radon accumulation, which poses a long-term health hazard due to its association with lung cancer [21].

Poor IAQ in libraries can have adverse health effects on occupants, including respiratory issues, allergies, and discomfort. Optimal IAQ levels contribute to occupant comfort, well-being, and productivity, enhancing the overall user experience in library spaces [22]. Poor IAQ can impair cognitive function and affect the learning and academic performance of library users. Studies have shown that exposure to indoor pollutants such as volatile organic compounds (VOCs) and carbon dioxide (CO₂) can lead to decreased concentration, memory impairment, and reduced productivity [23]. Libraries with poor IAQ may experience higher rates of absenteeism among staff and patrons due to health issues associated with indoor air pollution (Table 1). Respiratory symptoms, allergies, headaches, and fatigue resulting from exposure to indoor pollutants can contribute to increased sick leave and decreased productivity [6]. Prolonged exposure to indoor pollutants in libraries can pose significant health risks, particularly for vulnerable populations such as children, the elderly, and individuals with pre-existing health conditions. Poor IAQ has been linked to respiratory diseases, allergic reactions, asthma exacerbations, and other respiratory and cardiovascular problems [24]. Libraries are intended to be spaces for learning, research, and relaxation. However, poor IAQ can negatively impact the comfort and well-being of occupants, leading to dissatisfaction and avoidance of library facilities. Unpleasant odors, stuffy air, and visible signs of indoor pollution can create a negative perception of the library environment [25]. Addressing poor IAQ in libraries often requires energy-intensive solutions such as increased ventilation, air filtration, and humidity control. High energy consumption for HVAC systems and air quality improvement measures can result in elevated operational costs for library facilities, affecting budget allocation and sustainability efforts [26]. Libraries are subject to regulations and standards governing indoor air quality, health, and safety. Failure to maintain acceptable IAQ levels may result in legal liabilities, fines, and penalties. Compliance with building codes, occupational health regulations, and environmental standards is essential to ensure the well-being of library occupants and legal compliance [27].

Table 1: Pollutants and the effects on library user and environments.

Regulatory standards and guidelines, such as those provided by organizations like the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the Environmental Protection Agency (EPA), establish criteria for acceptable IAQ levels and provide recommendations for IAQ management practices in indoor environments [27,28]. Occupational safety and health regulations, enforced by governmental agencies such as the Occupational Safety and Health Administration (OSHA) in the United States, establish requirements for maintaining safe and healthy working conditions, including IAQ standards. These regulations may specify permissible exposure limits (PELs) for indoor pollutants and ventilation requirements to protect the health and safety of library staff and patrons [29]. Building codes and standards provide guidelines for the design, construction, and operation of buildings, including requirements related to IAQ. Organizations such as the International Code Council (ICC) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) develop and update building codes and standards that incorporate IAQ considerations, ventilation rates, and indoor pollutant control measures [30,27]. Green building certification programs, such as Leadership in Energy and Environmental Design (LEED) and Building Research Establishment Environmental Assessment Method (BREEAM), encourage the adoption of sustainable building practices, including IAQ management. These certification programs promote strategies such as efficient ventilation systems, low-emission building materials, and occupant engagement to improve IAQ and overall environmental performance [31,31]. National and international organizations, such as the World Health Organization (WHO) and the Environmental Protection Agency (EPA), publish indoor air quality guidelines that provide recommendations for acceptable IAQ levels and exposure limits for indoor pollutants. These guidelines serve as references for policymakers, building designers, and facility managers in assessing and improving IAQ in various indoor environments, including libraries [33,28]. Public health regulations may include requirements for monitoring and addressing IAQ issues in public buildings, including libraries, to protect the health and well-being of the community. Local health departments or environmental agencies may enforce regulations related to IAQ, indoor pollutant emissions, and ventilation systems in public facilities, ensuring compliance with health and safety standards [34].

his review adopted a systematic and comprehensive approach to gather and analyze relevant research on the topic of indoor air quality in library environments. Multiple academic databases were utilized, including Google Scholar, Web of Science, PsycINFO, and ERIC. A combination of search terms was used, including "indoor air quality," "libraries," "library environment," "health effects," "psychological impacts," "health and safety standards," "IQA management strategies," “National and international organizations” and "user experience." Studies were included if they: focused on the effects of air pollution in libraries specifically, published in peer-reviewed academic journals or reputable sources. published within the last 10 years (to ensure the inclusion of recent advancements in the field), available in English language, presented original research findings, reviews, or meta-analyses, and studies focusing solely on other types of noise pollution outside of libraries, non-peer-reviewed sources, and opinion pieces were excluded.

All retrieved references were initially screened to remove duplicates using reference management software. Based on the inclusion and exclusion criteria, titles and abstracts were independently reviewed by two reviewers to identify relevant studies. Disagreements were resolved through discussion or consultation with a third reviewer.

The full-text versions of the shortlisted studies were thoroughly reviewed to assess their relevance and quality. Studies not meeting the inclusion criteria or deemed irrelevant after closer examination were excluded. A standardized data extraction form was used to collect relevant information from the included studies, including:  Study design (e.g., observational, experimental), Participants (e.g., library users, students), air pollution sources and monitoring methods, Assessed impacts of IAQ (e.g., cognitive, psychological, and physiological), Implemented IAQ management strategies (if applicable), and Findings and conclusions. The extracted data was then categorized and analyzed thematically to identify key themes, trends, and gaps in the existing research.

The Individual Factors Contributing To Indoor Air Quality in Library Environments

Temperature: Maintaining an appropriate temperature range in a library is essential for the comfort of patrons and staff. Temperature can also impact the rate of chemical reactions that may affect the materials in the library, such as books, paper, and electronic devices. Extreme temperatures can lead to the deterioration of materials over time.

Temperature and Relative Humidity: Fluctuations in temperature and humidity levels can accelerate the degradation of library materials. High humidity can promote mold growth and insect infestations, while low humidity can cause materials to become brittle [35]. Maintaining stable temperature and humidity levels within recommended ranges is crucial for preserving books and other materials.

Figure 2: Factors of Effects on Environment.

Humidity: Controlling humidity levels is crucial for preserving library materials, as high humidity can promote mold growth and insect infestations, while low humidity can cause materials to become brittle and deteriorate. Maintaining relative humidity within the recommended range (typically around 30-50%) is important for the long-term preservation of books and other materials.

Particulate Matter: Particulate matter in the air, such as dust, pollen, and soot, can accumulate on surfaces in the library, including books and shelves. Regular cleaning and air filtration can help reduce the levels of particulate matter in the indoor environment, improving air quality and preserving library materials.

Volatile Organic Compounds (VOCs): VOCs are chemicals that can off-gas from building materials, furniture, cleaning products, and other sources in the library. Prolonged exposure to high levels of VOCs can have adverse health effects and may also contribute to the deterioration of library materials. Proper ventilation and the use of low-VOC products can help reduce VOC concentrations in the indoor environment. Exposure to particulate matter and volatile organic compounds (VOCs) in the air can lead to the soiling and degradation of library materials. Particulate matter can accumulate on surfaces, including books, while VOCs can cause chemical degradation and discoloration of materials [36]. Proper air filtration and ventilation can help reduce the levels of these pollutants and protect library collections.

Carbon Dioxide (CO2) Levels: Monitoring carbon dioxide levels is important for assessing ventilation adequacy in library spaces. Elevated CO2 levels can indicate poor ventilation, which may result in a buildup of other indoor air pollutants and compromise air quality. Proper ventilation design and maintenance are essential for ensuring adequate air exchange rates and maintaining healthy indoor air quality.

Biological Contaminants: Biological contaminants such as mold, bacteria, and allergens can thrive in damp or poorly ventilated environments, posing health risks to library occupants and contributing to the deterioration of materials. Regular inspection, maintenance of HVAC systems, and prompt remediation of water leaks are important measures for preventing the growth of biological contaminants in library settings. By addressing these individual factors and implementing appropriate strategies for maintaining indoor air quality, libraries can create healthier and more sustainable environments that promote the preservation of valuable materials and the well-being of patrons and staff. Mold and other biological contaminants can thrive in damp indoor environments, posing risks to both the health of library users and the preservation of materials. Biological contaminants can cause staining, odors, and physical damage to books and other materials. Regular inspection and maintenance are essential for preventing the growth of these contaminants [6]. Indoor air quality can have a significant impact on the preservation of library books and materials.

The Potential Health Risks Associated With Poor Air Quality in Libraries

Poor air quality in libraries can pose potential health risks to library users and staff. Here are some key health risks associated with poor indoor air quality in libraries, supported by references:

Respiratory Issues: Exposure to indoor air pollutants such as particulate matter, volatile organic compounds (VOCs), and mold spores can contribute to respiratory issues such as asthma and allergies [28]. Poor indoor air quality can exacerbate existing respiratory conditions and lead to discomfort and health problems among library occupants.

Headaches and Fatigue: High levels of indoor air pollutants, inadequate ventilation, and poor air quality can result in symptoms such as headaches, fatigue, and difficulty concentrating [37]. These symptoms can impact the well-being and productivity of individuals spending time in library spaces.

Allergic Reactions: Mold growth due to high humidity levels in libraries can trigger allergic reactions in sensitive individuals, leading to symptoms such as sneezing, coughing, and skin irritation [34]. Exposure to mold spores can exacerbate allergies and respiratory conditions in library users.

Eye Irritation and Discomfort: Indoor air pollutants and contaminants can cause eye irritation and discomfort among library occupants. Symptoms may include redness, itching, and watering of the eyes, which can impact the overall comfort of individuals in the library environment. By addressing indoor air quality issues and implementing measures to improve air quality in libraries, such as proper ventilation, regular maintenance, and monitoring of air quality parameters, libraries can create healthier and more comfortable indoor environments for their patrons and staff.

Cognitive Impairment: Exposure to indoor air pollutants, such as volatile organic compounds (VOCs) and particulate matter, can have negative effects on cognitive function and mental health. Studies have shown that poor indoor air quality can impair cognitive performance, memory, and decision-making abilities among individuals [23].

Sensory Irritation: Poor indoor air quality can lead to sensory irritation symptoms such as dry or itchy skin, throat irritation, and nasal congestion. Exposure to indoor air pollutants can cause discomfort and affect the overall well-being and comfort of individuals in library settings [37].

Long-Term Health Effects: Prolonged exposure to poor indoor air quality in libraries can lead to long-term health effects, including respiratory diseases, cardiovascular issues, and neurological disorders. Chronic exposure to indoor air pollutants may increase the risk of developing serious health conditions over time [28].

By addressing these potential health risks associated with poor indoor air quality in libraries and implementing strategies to improve air quality, libraries can create healthier and safer environments for their patrons and staff, promoting overall well-being and pro

Air Quality Impact on Library Environments: The quality of air within library environments has a significant impact on the well-being and productivity of visitors and staff. Poor air quality can lead to health issues, discomfort, and decreased cognitive function.

Common Air Pollutants: Libraries can be exposed to various air pollutants, including dust, mold spores, volatile organic compounds (VOCs), and particulate matter. These pollutants can originate from sources such as building materials, furniture, cleaning products, and outdoor air pollution.

Ventilation and Filtration Systems: Proper ventilation and filtration systems are crucial for maintaining good indoor air quality in libraries. Inadequate ventilation can lead to the accumulation of pollutants, while effective filtration can help remove harmful particles from the air.

Importance of Monitoring: Regular monitoring of air quality parameters such as particulate levels, humidity, and carbon dioxide concentrations is essential for identifying potential issues and ensuring a healthy indoor environment.

Regular Maintenance of HVAC Systems: Libraries should implement a regular maintenance schedule for their heating, ventilation, and air conditioning (HVAC) systems to ensure optimal performance and air quality. This includes changing filters, cleaning ducts, and inspecting for any issues.

Use of Air Purifiers: Consider installing air purifiers with HEPA filters in key areas of the library to help remove airborne pollutants and improve overall air quality.

Green Cleaning Practices: Use environmentally friendly cleaning products to reduce the emission of harmful chemicals into the air. Implementing green cleaning practices can help maintain a healthier indoor environment.

Promote Natural Ventilation: Where possible, encourage natural ventilation by opening windows and doors to bring in fresh air. This can help dilute indoor pollutants and improve air circulation.

Education and Awareness: Raise awareness among library staff and visitors about the importance of air quality in maintaining a healthy environment. Provide guidance on best practices for improving air quality and encourage collaboration in maintaining a clean and healthy space. By implementing these recommendations and staying vigilant about air quality monitoring, libraries can create a healthier and more comfortable environment for all occupants.

1. Abu Hussein HM, Salama HE, Alshaer W. Building characteristics and indoor air quality: a comprehensive review. Building Services Engineering Research and Technology. 2019; 40: 139-153.
2. Kumar P, Adhikari A, Mukhopadhyay A. HVAC: Handbook of Heating, Ventilation and Air Conditioning for Design and Implementation. CRC Press. 2018.
3. Azuma K, Yanagi U, Osawa H, Yoshikado H, Ito T. The Impact of HVAC Filtration on Indoor Air Quality. International Journal of Environmental Research and Public Health. 2017; 14: 749.
4. Tang Y, Chen W, Chen J, Chen Q. Review of natural ventilation in high-rise buildings. Building Simulation. 2020; 13: 295-314.
5. Ahmed T, Soebarto V, Thanh T. Material selection for sustainable building construction: A review of the implications of green building materials on building life cycle energy and carbon footprint. Buildings. 2019; 9: 94.
6. Park SS, Fisk WJ. The influence of ventilation and filtration on indoor airborne particle concentrations in a school classroom. Indoor Air. 2019; 29: 956-967.
7. Lee E, Park J, Lee YH, Choi J. Effects of layout design on indoor air quality in classrooms using the computational fluid dynamics simulation. Indoor and Built Environment. 2018; 27: 516-526.
8. Wolkoff P. Indoor air humidity, air quality, and health – An overview. International Journal of Hygiene and Environmental Health. 2018; 221: 376-390.
9. Liu J, Zhou Y, Liu Y. Dust emissions from books in libraries. Aerosol and Air Quality Research. 2019; 19: 984-991.
10. Wang J, Wang S, Wang J, Zhang X, Xu C, Zhang Y. Volatile organic compounds and particulate matter in indoor air: A comparative study of indoor pollution in public places in Hangzhou, China. International Journal of Environmental Research and Public Health. 2017; 14: 85
11. Hao L, Tian Y, Zhang X, Zhu J. Influence of different operating conditions on the release of volatile organic compounds from laser printers and photocopiers. Environmental Science and Pollution Research. 2020; 27: 27635-27646.
12. Wei W, Cao J, Fu J. An investigation of the indoor air quality in university libraries: A case study in Changsha, China. Building and Environment. 2018; 136: 230-237.
13. Sze-To GN, Ong KC, Qian H, Wong LT. Exposure to air pollutants in different indoor environments: A review. Indoor Air. 2020; 30: 629-642.
14. Liu J, Zhu T, Wang D. The effect of personal behaviors on airborne infection risk in indoor environments: A review. Building and Environment. 2021; 197: 107817.
15. Zhang C, Zhang R, Liu H, Zhang Y, Ye W. Influence of library construction design on indoor air quality. IOP Conference Series: Materials Science and Engineering. 2020; 770: 012019
16. Zhang Y, Mo J, Li Y, Sundell J, Wargocki P. Ventilation and indoor air quality in new homes in Hangzhou, China. Indoor Air. 2019; 29: 819-831.
17. Wolkoff P. Indoor air pollutants in office environments: Assessment of comfort, health, and performance. International Journal of Hygiene and Environmental Health. 2020; 227: 113515.
18. Weschler CJ, Carslaw N. Indoor chemistry. Environmental Science & Technology Letters. 2018; 5: 167-175.
19. Douwes J, Thorne P, Pearce N, Heederik D. Bioaerosol health effects and exposure assessment: Progress and prospects. Annals of Work Exposures and Health. 2018; 62: 363-374.
20. Huang L, Liu S, Kang Y, Sun Y, Liu Y. Indoor ozone pollution: A review of current knowledge and future perspectives. Building and Environment. 2021; 194: 107629.
21. Barros N, Silva JE, Barbosa SM, Pereira AJSC. Assessment of radon concentration in indoor air of libraries from the Aveiro University, Portugal. Science of the Total Environment. 2020; 741: 140166.
22. Nazaroff WW, Weschler CJ. Cleaning products and air fresheners: exposure to primary and secondary air pollutants. Atmospheric Environment. 2004; 38: 2841-2865.
23. Mendell MJ. Indoor environmental quality and student performance. Building and Environment. 2016; 109: 159-160.
24. Sundell J, Levin H, Nazaroff WW. Ventilation rates and health: multidisciplinary review of the scientific literature. Indoor Air. 2011; 21: 191-204.
25. Park JH, Fisk WJ. Trends in building energy codes and standards impact indoor environmental quality. Building and Environment. 2015; 93: 554-562.
26. Lu Y, Yin H, Morawska L. The energy consumption implications of improved indoor air quality for Chinese office buildings. Building and Environment. 2018; 138: 1-8.
27. ASHRAE Standard 62.1-2019: Ventilation for Acceptable Indoor Air Quality. Atlanta, GA: American Society of Heating. Refrigerating and Air-Conditioning Engineers. 2019.
28. Indoor Air Quality (IAQ). 2020.
29. Indoor Air Quality (IAQ) in Commercial and Institutional Buildings. Occupational Safety and Health Administration. 2021.
30. International Codes. International Code Council. 2021.
31. LEED Certification. U.S. Green Building Council. 2021.
32. BREEAM Certification. Building Research Establishment. Retrieved from. 2021.
33. WHO Guidelines for Indoor Air Quality: Selected Pollutants. World Health Organization. 2018.
34. Indoor Environmental Quality in Schools and Child Care Facilities. Centers for Disease Control and Prevention. 2021.
35. Arundel AV, Sterling EM, Biggin JH, Sterling TD. Indirect health effects of relative humidity in indoor environments. Environmental Health Perspectives. 1986; 65: 351-361.
36. Weschler CJ, Nazaroff WW. Semivolatile organic compounds in indoor environments. Atmospheric Environment. 2008; 42: 9018-9040.
37. WHO Guidelines for Indoor Air Quality: Selected Pollutants. World Health Organization. 2018.
38. Persily AK. Indoor air quality in high-performance buildings. ASHRAE Journal. 1997; 39: 26-32.
39. World Health Organization. WHO global air quality guidelines: particulate matter (‎PM2.5 and PM10)‎, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. World Health Organization. 2021‎.