Health Aspects of Air Pollution with Particulate Matter, Ozone and Nitrogen Dioxide



Detailed knowledge on the effects of air pollutants on human health is a prerequisite for the development of effective policies to reduce the adverse impact of ambient air pollution. The second edition of WHO's Air quality guidelines (AQG) for Europe, formulated in 1996, summarizes systematically the effects of several air pollutants. These guidelines have been used extensively to establish regulatory frameworks for air quality assessment and management. To support the development of European Union policy on clean air for Europe (CAFÉ), this WHO Working Group (WG) was convened to review systematically the most recent scientific evidence on the adverse health effects of particulate matter (PM), ozone (O3) and nitrogen dioxide (NO2). The review focused on studies that were published after the second edition of the WHO AQG was produced, and which have been influential in changing our views on health-related aspects of the substances under consideration. The WG adopted a recommendation to use fine particulate matter, (PM2.5), as the indicator for health effects induced by particulate pollution such as increased risk of mortality in Europe, to supplement the commonly used PM10 (which includes fine and coarse particles). It also acknowledged the evidence that ozone produces short-term effects on mortality and respiratory morbidity, even at the low ozone concentrations experienced in many cities in Europe. Based on these findings the WG recommended that WHO should update exposure-response relationships for the most severe health outcomes induced by particulate matter and ozone presented by AQGs. The WG also concluded that an update of the current WHO AQG for nitrogen dioxide, which is also an important precursor for the formation of ozone and particulate matter, was not warranted.