Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide

Overview

The WHO air quality guidelines are designed to offer guidance in reducing the health impacts of air pollution. First produced in 1987 and updated in 1997, these guidelines are based on expert evaluation of current scientific evidence. Given the wealth of new studies on the health effects of air pollution that has been published in the scientific literature since the completion of the second edition of the Air Quality Guidelines for Europe, including important new research from low-and middle-income countries where air pollution levels are at their highest, WHO has undertaken to review the accumulated scientific evidence and to consider its implications for its air quality guidelines. The result of this work is presented in this document in the form of revised guideline values for selected air pollutants, which are applicable across all WHO regions.

These guidelines are intended to inform policy-makers and to provide appropriate targets for a broad range of policy options for air quality management in different parts of the world. The new information included in this latest update of the Air quality guidelines relate to four common air pollutants: particulate matter (PM), ozone (O3 ), nitrogen dioxide (NO2 ) and sulfur dioxide (SO2 ). The scope of this review reflects the availability of new evidence on the health effects of these pollutants and their relative importance with regard to current and future health effects of air pollution in each of the WHO regions. For air pollutants not considered in the present document the conclusions presented in the WHO Air quality guidelines for Europe 3 remain in effect.