WHO Air Quality Guidelines for Europe.

This article describes the WHO Air Quality Guidelines and highlights two projects that were initiated to update the risk assessment of the main air pollutants: "Systematic Review of Health Aspects of Air Quality in Europe" and the "Global Update of WHO Air Quality Guidelines." The report of the Systematic Review emphasizes that the accumulated evidence is sufficient to require actions reducing the health impacts of air pollution in Europe. The global update of the air quality guidelines focuses on particulate matter (PM), ozone, NO2, and SO2 and addresses issues associated with the practical feasibility of attaining the guidelines in developing countries. The article illustrates WHO's activities toward gathering the best available international scientific evidence to support air quality policy development in all regions of the world.