World Health Organization Guidelines
This page summarizes the World Health Organization's (WHO) position and guidelines concerning indoor air quality (IAQ), drawing from various WHO publications issued between 1987 and 2023.
The World Health Organization (WHO) plays a crucial role in establishing global air quality guidelines to protect public health from the adverse effects of air pollution. Recognizing that air pollution is the single biggest environmental threat to human health, the WHO has been periodically issuing evidence-based recommendations since 1987[1].
WHO's Stance on Indoor Air Quality
Clean air is recognized by WHO as a basic requirement for human health and wellbeing. Since people spend a significant portion of their time indoors, indoor air quality is a critical determinant of health. WHO emphasizes that indoor air pollution is a major cause of morbidity and mortality worldwide. Problems like dampness, mould, and emissions from building materials, consumer products, and combustion activities (heating, cooking) contribute substantially to this burden.
WHO's primary aim in issuing air quality guidelines is to provide a basis for protecting public health from the adverse effects of air pollution and for eliminating or reducing hazardous air contaminants to a minimum. These guidelines are intended to inform risk management decisions, particularly in setting standards, but are not standards in themselves. National authorities must consider these guidelines within the context of local environmental, social, and economic conditions. WHO stresses that efforts should always be made to keep air pollution levels as low as practically achievable.
The WHO guidelines cover various indoor pollutants such as particulate matter, volatile organic compounds (VOCs), mold, and radon, offering comprehensive strategies to mitigate these risks.
Evolution of WHO Air Quality Guidelines
WHO's concern with air pollution dates back decades. Key milestones relevant to IAQ include:
- 1987: Air Quality Guidelines for Europe[1]: This first edition assessed 28 chemical contaminants, recognizing the importance of indoor air quality and including pollutants often found indoors. It established different approaches for non-carcinogens (threshold-based guideline values) and carcinogens (risk estimation).
- 2000: Air Quality Guidelines for Europe (Second Edition)[2]: This edition updated the previous guidelines, reflecting new scientific data and risk assessment methodologies. It expanded the list of pollutants and included a dedicated section on indoor air pollutants like environmental tobacco smoke (ETS), man-made vitreous fibres, and radon. The applicability of guidelines to both indoor and outdoor air (except where specified) was maintained.
- 2005: Global Update (AQG 2005): Focused on particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2), providing updated guideline levels applicable globally and in all environments, including indoors. It introduced the concept of interim targets for PM, ozone, and SO2 as steps for highly polluted areas.
- 2009: WHO Guidelines for Indoor Air Quality: Dampness and Mould[3]: Addressed biological contaminants, concluding that sufficient evidence links dampness and mould to respiratory symptoms, allergies, and asthma exacerbation. Due to the complexity of microbial exposures, it recommended preventing/minimizing dampness and microbial growth rather than setting numerical limits for biological agents.
- 2010: WHO Guidelines for Indoor Air Quality: Selected Pollutants[4]: Provided specific guideline values or risk estimates for nine key indoor pollutants: benzene, carbon monoxide (CO), formaldehyde, naphthalene, nitrogen dioxide (NO2), polycyclic aromatic hydrocarbons (PAHs), radon, trichloroethylene (TCE), and tetrachloroethylene.
- 2014: WHO Guidelines for Indoor Air Quality: Household Fuel Combustion[5]: Focused specifically on the significant health risks from burning solid fuels and kerosene in households, providing emission rate targets (ERTs) for stoves and fuels needed to meet WHO AQG levels for PM2.5 and CO. It strongly discouraged the household use of unprocessed coal and kerosene.
- 2021: WHO Global Air Quality Guidelines[6]: Provided updated, lower AQG levels for PM2.5, PM10, O3, NO2, SO2, and CO, based on a substantial increase in evidence showing adverse health effects at lower concentrations than previously understood. It retained the concept of interim targets and added good practice statements for specific PM types like black carbon/elemental carbon (BC/EC), ultrafine particles (UFP), and sand/dust storm particles.
Policy and Implementation
WHO guidelines provide a crucial scientific foundation for developing national air quality standards, although they are not legally binding in themselves. The transition from these international guidelines to enforceable national standards necessitates careful consideration of local contexts, including technical feasibility, socioeconomic factors, and political decisions regarding acceptable risk levels and the protection of vulnerable populations. Serving as critical references, the guidelines, including any interim targets, allow countries to benchmark progress, evaluate the effectiveness of air quality management strategies, shape global health policy, advocate for cleaner indoor environments, and ultimately drive legislative changes and policy measures to mitigate air pollution and improve public health.
Effective air quality management requires:
- Monitoring: Assessing current air quality levels.
- Source control: Reducing emissions from major sources like traffic, industry, household fuel combustion, and building materials. For indoor air, this includes using low-emission materials, proper venting of combustion appliances, and controlling activities like smoking.
- Ventilation: Ensuring adequate exchange between indoor and outdoor air to dilute indoor pollutants and control humidity, while considering the quality of outdoor air and energy efficiency.
- Policy integration: Addressing air quality across sectors (health, energy, environment, transport, housing) and involving multiple stakeholders.
- Public awareness and communication: Informing the public about risks and protective measures.
References
- ↑ 1.0 1.1 World Health Organization. (1987). Air quality guidelines for Europe.
- ↑ World Health Organization. (2000). Air quality guidelines for Europe (2nd edition).
- ↑ World Health Organization. (2009). WHO guidelines for indoor air quality: dampness and mould.World Health Organization. (2010). WHO guidelines for indoor air quality: selected pollutants.
- World Health Organization. (2014). WHO Guidelines for indoor air quality: Household fuel combustion.
- World Health Organization. (2021). WHO global air quality guidelines: particulate matter (PM2. 5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide.
- World Health Organization. (2023, September 26). Household air pollution and health (Fact sheet).
European Union
- European Parliament & Council. (2008, May 21). Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe. Official Journal of the European Union
- European Parliament & Council. (2024, October 23). Directive (EU) 2024/2881 of 23 October 2024 on ambient air quality and cleaner air for Europe (recast). Official Journal of the European Union
- European Commission: Directorate-General for Environment. (2022). Study to support the impact assessment for a revision of the EU Ambient Air Quality Directives: final report. Publications Office of the European Union.
- European Commission. EU clean air policy.
- European Commission: Directorate-General for Environment. EU air quality standards.
Zero Pollution Action Plan (ZPAP)
- European Commission. (2021). EU Action Plan: 'Towards Zero Pollution for Air, Water and Soil'.
- European Commission. (2021) Zero Pollution Action Plan.
- European Commission: Directorate-General for Research and Innovation. (2022). Horizon projects supporting the zero pollution action plan. Publications Office of the European Union.
- European Commission, J.R.C. (2022). Zero Pollution Outlook 2022. Publications Office of the European Union.
Outdoor air
- European Commission. (2022) Revision of the Ambient Air Quality Directives.
European Environment Agency (EEA)
- European Environment Agency. (2019). Healthy environment, healthy lives: how the environment influences health and well-being in Europe. (Report)
- European Environment Agency. (2020). Air quality in Europe — 2020 report. (Report)
- European Environment Agency. (2020). Air pollution and children's health. (Briefing no. 07/2023)
- European Environment Agency. (2025). Air quality status report 2025. (Web report)
Scientific papers
- van den Brekel, L., Lenters, V., Mackenbach, J. D., Hoek, G., Wagtendonk, A., Lakerveld, J., ... & Vaartjes, I. (2024). Ethnic and socioeconomic inequalities in air pollution exposure: a cross-sectional analysis of nationwide individual-level data from the Netherlands. The Lancet Planetary Health, 8(1), e18-e29.
- Dimitroulopoulou, S., Dudzińska, M. R., Gunnarsen, L., Hägerhed, L., Maula, H., Singh, R., ... & Haverinen-Shaughnessy, U. (2023). Indoor air quality guidelines from across the world: An appraisal considering energy saving, health, productivity, and comfort. Environment International, 178, 108127.
- Fuller, R., Landrigan, P. J., Balakrishnan, K., Bathan, G., Bose-O'Reilly, S., Brauer, M., ... & Yan, C. (2022). Pollution and health: a progress update. The Lancet Planetary Health, 6(6), e535-e547.
- Halios, C. H., Landeg-Cox, C., Lowther, S. D., Middleton, A., Marczylo, T., & Dimitroulopoulou, S. (2022). Chemicals in European residences–Part I: A review of emissions, concentrations and health effects of volatile organic compounds (VOCs). Science of the Total Environment, 839, 156201.
- Hossain, M. P., Zhou, W., Leung, M. Y., & Yuan, H. Y. (2024). Association of air pollution and weather conditions during infection course with COVID-19 case fatality rate in the United Kingdom. Scientific reports, 14(1), 683.
- Jacobson, T. A., Kler, J. S., Hernke, M. T., Braun, R. K., Meyer, K. C., & Funk, W. E. (2019). Direct human health risks of increased atmospheric carbon dioxide. Nature Sustainability, 2(8), 691–701.
- Laurent, É. (2022). Air (ine) quality in the European Union. Current Environmental Health Reports, 9(2), 123-129.
- Sadrizadeh, S., Yao, R., Yuan, F., Awbi, H., Bahnfleth, W., Bi, Y., ... & Li, B. (2022). Indoor air quality and health in schools: A critical review for developing the roadmap for the future school environment. Journal of Building Engineering, 57, 104908.
- Settimo, G., Manigrasso, M., & Avino, P. (2020). Indoor air quality: A focus on the European legislation and state-of-the-art research in Italy. Atmosphere, 11(4), 370.
Books
- Hippocrates. (1923). Airs, waters, places. In Hippocrates (Vol. 1, pp. 65–137). (W. H. S. Jones, Trans.). William Heinemann; Harvard University Press. (Original work published ca. 400 B.C.E.)
- Zhang, Y., Hopke, P. K., & Mandin, C. (Eds.). (2022). Handbook of indoor air quality. Springer Nature.
Other
Popova, D. (2023, October 24). Air equity: Unravelling the pollution puzzle in Sofia’s largest Roma neighborhood. Clean Air Fund. - ↑
- ↑ World Health Organization. (2014). WHO Guidelines for indoor air quality: Household fuel combustion.
- ↑ World Health Organization. (2021). WHO global air quality guidelines: particulate matter (PM2. 5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide.
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