WHO global air quality guidelines: particulate matter (‎PM2.5 and PM10)‎, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide

The WHO Global Air Quality Guidelines set the levels of air quality for a number of pollutants to be achieved everywhere in order to significantly reduce the adverse health effects of pollution. They also include interim targets which are incremental steps in the reduction of air pollution and are intended for use in areas where pollution is high towards ultimately achieving air quality guideline (AQG) levels.