A recent WHO publication reviews the key health effects of several common indoor air pollutants, with a view to presenting air quality guidelines for the protection of human health.

For formaldehyde, a short-term (30-minute) guideline of 0.1 mg/m3 was recommended in order to prevent sensory irritation in the general population, a level that was also thought to be protective for chronic exposure. In the case of naphthalene, a long-term guideline value of 0.01 mg/m3 was proposed (which should be applied as an annual average), while for carbon monoxide, a series of guidelines relevant to typical indoor exposures was recommended (ranging from 100 mg/m3 for 15 minutes, down to 7 mg/m3 for 24 hours). Evaluations on tetrachloroethylene and nitrogen dioxide supported guideline values previously developed by WHO for annual average exposures (0.25 mg/m3 and 40 µg/m3, respectively), and for short term (1-hour) exposure of nitrogen dioxide (200 µg/m3).

For some pollutants, the plausibility of a human cancer risk led to the recommendation of a non-threshold approach with risk estimations (rather than guideline values) being determined. Unit risk estimates (for specific cancers) were calculated for benzo[a]pyrene (as a typical polycyclic aromatic hydrocarbon), benzene and trichloroethylene at 8.7 x 10-5 per ng/m3, 6 x 10-6 per µg/m3 and 4.3 x 10-7 per µg/m3, respectively. These values were equivalent to excess lifetime cancer risks of one in 100,000 at concentrations of 0.12 ng/m3 benzo[a]pyrene, 1.7 µg/m3 benzene and 23 µg/m3 trichloroethylene.

[World Health Organization (2010). WHO guidelines for indoor air quality: selected pollutants. The full report is available at http://www.euro.who.int/__data/assets/pdf_file/0009/128169/e94535.pdf on the WHO website.] {187186}

The above item was taken from the April 2011 issue of Toxicology and Regulatory News which is sent automatically to members of bibra (click here for more details). 

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