WHO Guidelines for Indoor Air Quality: Selected Pollutants
About this book
The WHO Guidelines for Indoor Air Quality: Selected Pollutants, published in 2010, represent the most comprehensive international scientific assessment of the health risks posed by indoor air pollution and the evidence base for establishing health-protective guideline values. The document covers nine priority indoor air pollutants selected for their prevalence, the severity of their health effects, and the availability of sufficient scientific evidence to establish quantitative exposure-response relationships. The nine pollutants covered are: benzene, carbon monoxide (CO), formaldehyde, naphthalene, nitrogen dioxide (NO2), polycyclic aromatic hydrocarbons (PAH), radon, trichloroethylene, and tetrachloroethylene.
For each pollutant, the guidelines provide: a description of sources in indoor environments (building materials, combustion, outdoor infiltration); a summary of exposure assessment studies showing typical indoor concentration ranges; a systematic review of epidemiological and toxicological evidence on health effects; and the derivation of guideline values where sufficient evidence exists. The health effects covered range from acute toxicity at high exposures — the life-threatening carbon monoxide poisoning that kills hundreds of people annually — to chronic low-level exposures associated with elevated cancer risk. Benzene, radon, and PAH are classified as human carcinogens; formaldehyde as a probable carcinogen; and nitrogen dioxide, a combustion product from gas appliances and outdoor traffic, is associated with respiratory inflammation and exacerbation of asthma.
The guidelines are directly relevant to building design and materials selection. Formaldehyde, for example, is emitted by a wide range of common building products including pressed wood products, adhesives, and finishes; the guideline value of 0.1 mg/m³ as a long-term average has influenced both product regulations and ventilation requirements in building codes globally. Radon, a radioactive gas that seeps from underlying soils, requires specific building design measures in high-risk geological zones.
These guidelines informed the development of the more comprehensive 2021 WHO Global Air Quality Guidelines and remain the primary reference for indoor-specific pollutants in building regulations and health impact assessments. Sources: World Health Organization (who.int); WHO Guidelines for Indoor Air Quality: Selected Pollutants 2010 official publication.