title: Time to harmonize national ambient air quality standards.
abstract: OBJECTIVE
  The 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.
  
  
  METHODS
  We 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.
  
  
  RESULTS
  We 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, PM10and SO2poorly complied with WHO guideline values. The agreement was higher for CO, SO2(10-min averaging time) and NO2.
  
  
  CONCLUSIONS
  Regulatory 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.
authors.affiliation: Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland. meltem.kutlar@unibas.ch.|University of Basel, Basel, Switzerland. meltem.kutlar@unibas.ch.
authors.forename: Meltem
authors.initials: M
authors.lastname: Kutlar Joss
authors.affiliation: Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland.|University of Basel, Basel, Switzerland.
authors.forename: Marloes
authors.initials: M
authors.lastname: Eeftens
authors.affiliation: Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland.|University of Basel, Basel, Switzerland.
authors.forename: Emily
authors.initials: E
authors.lastname: Gintowt
authors.affiliation: Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland.|University of Basel, Basel, Switzerland.
authors.forename: Ron
authors.initials: R
authors.lastname: Kappeler
authors.affiliation: Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland.|University of Basel, Basel, Switzerland.
authors.forename: Nino
authors.initials: N
authors.lastname: Künzli
mesh_terms: D000393:Air Pollutants / Q000592:standards*; D000397:Air Pollution / Q000009:adverse effects*; D002248:Carbon Monoxide / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods / Q000592:standards*; D014943:Global Health; D006801:Humans; D009585:Nitrogen Dioxide / Q000032:analysis; D010126:Ozone / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D013458:Sulfur Dioxide / Q000032:analysis; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide
keywords: Air pollution; Air quality; Limit values; Particulate matter; Policy; Standards