ObjectivesThe World Health Organization has developed ambient air quality guidelines at levels considered to be safe or of acceptable risk for human health. These guidelines are meant to support governments in defining national standards. It is unclear how they are followed.MethodsWe compiled an inventory of ambient air quality standards for 194 countries worldwide for six air pollutants: PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide and carbon monoxide. We conducted literature and internet searches and asked country representatives about national ambient air quality standards.ResultsWe found information on 170 countries including 57 countries that did not set any air quality standards. Levels varied greatly by country and by pollutant. Ambient air quality standards for PM2.5, PM10 and SO2 poorly complied with WHO guideline values. The agreement was higher for CO, SO2 (10-min averaging time) and NO2.ConclusionsRegulatory differences mirror the differences in air quality and the related burden of disease around the globe. Governments worldwide should adopt science based air quality standards and clean air management plans to continuously improve air quality locally, nationally, and globally.Electronic supplementary materialThe online version of this article (doi:10.1007/s00038-017-0952-y) contains supplementary material, which is available to authorized users.

This editorial is part of the special issue ''Driving the Best Science to Meet Global Health Challenges'' edited on the occasion of the 9th European Congress on Tropical Medicine and International Health 2015.

Unfortunately, the table shows the past rather than the current long-term air quality standards for the USA. As of 2015, the US has no federal annual mean standard for PM10 whereas the PM2.5 standard has been set at 12 lg/m 3. China has partially set stricter long-term targets for PM in larger cities which will be valid nationwide by 2016 (70 lg PM10/m 3 and 35 lg PM2.5/m 3). Country or agency PM 10 lg m-3 PM 2.5 lg m-3