To update the WHO Air quality guidelines (AQG), and to assure their global applicability, WHO established a working group consisting of experts in epidemiology, toxicology, air quality exposure assessment, air quality management, and public policy. Based on the review of the newly accumulated evidence on health aspects of air pollution, the working group agreed on the updated guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide. To facilitate implementation of the guidelines in all WHO Regions, especially in more polluted areas, the group recommended interim targets which, if achieved, would result in significant reductions in pollutant-related health risks and would indicate a progress towards the guideline values.

Table 2.6.2-1 below summarizes the updated WHO Air quality guideline levels. They are recommended to be achieved everywhere in order to significantly reduce the adverse health effects of pollution.