Health Aspects of Air Pollution - answers to follow-up questions from CAFE

Air pollution has a significant impact on human health in Europe. In order to design policies to decrease the health impacts of air pollution effectively, detailed knowledge on these effects is required. This WHO working group developed guidance for the European Commission to support the European Community Clean Air For Europe (CAFE) programme. It is supplementary to the report “Health Aspects of Air Pollution with Particulate Matter, Ozone and Nitrogen Dioxide”, which was published in spring 2003 by WHO.

The Working Group recognized that the large variations in individuals’ susceptibilities within larger populations, when combined with more sophisticated (epidemiological) tools make it difficult to discern noeffect thresholds – which were previously widely used in establishing legally binding air quality standards – in population studies, and that the threshold concept may become meaningless at the general population level. Proper descriptions of concentration-response functions should be used instead. It also acknowledged the health relevance of both the exposure at hot spot locations, and the overall exposure of the population and recognized that an unequal distribution of health risks over the population would raise concerns of environmental justice and equity. The Working Group also recommended that the WHO Air Quality Guideline value for NO2 of 40 μg/m3 as annual mean should be retained or lowered. It also discussed different sources of uncertainties linked to the identification and quantification of health effects of air pollution in detail and concluded that the evidence is sufficient to recommend strongly further policy action to reduce levels of air pollutants including PM, nitrogen dioxide and ozone and that it is reasonable to assume that a reduction of air pollution will lead to considerable health benefits.