WHO outdoor air quality guidelines

Outdoor air pollution results from emissions from motor vehicles, industry, heating and commercial sources.
WHO air quality guidelines for outdoor air pollution represent the most widely accepted and up-to-date assessment of health effects of air pollution, recommending targets for air quality at which health risks are significantly reduced.

Air quality guidelines: the global update 2005

In the latest edition of its outdoor air quality guidelines (AQGs), published in 2005, WHO challenges governments around the world to improve air quality, to protect people's health, and to follow dramatically lower standards for levels of pollutants. The guidelines urge the elimination or reduction of a number of ambient air pollutants known to be hazardous to human health and well-being. They also provide a reference for setting national standards by indicating pollutant concentrations below which lifetime exposure or exposure for a given averaging time does not constitute a public health risk.

The 2005 AQGs global update indicates that reducing levels of one particular type of air pollutant (particulate matter) could decrease mortality in polluted cities by as much as 15% every year. It also substantially decreases the recommended limits for ozone and sulphur dioxide that were proposed in the previous edition of the AQGs in the year 2000. These targets are generally lower than the national legally binding standards currently applied in many parts of the world.

WHO has started in 2016 the revision process of the AQGs for outdoor air pollution, which will provide up-to-date recommendations on ambient pollutant concentrations in order to support policy makers and other decision-makers setting efficient standards and goals across the world for air quality management to protect public health.

WHO guidelines as reference for European Union policies

In line with WHO's guidelines, which identify fine particles (PM2.5) as one of the most dangerous pollutants for human health, the 2008 European Union (EU) directive on ambient air quality and cleaner air set objectives and target dates for reducing population exposure to PM2.5. It also maintained limits for concentration of larger particles (PM10) and other main pollutants already subject to legislation.

As part an EU assessment of the effectiveness of existing air quality policy, WHO completed in 2013 a comprehensive review of evidence on the health aspects of air pollution. The results of this review also assessed the need for WHO to start the process of updating the existing AQGs for a number of ambient air pollutants.