The WHO, in a review on the health effects of air pollution, has recommended that that the EU should have tighter air quality standards for pollutant PM2.5. Current EU law has a limit value of 25ug/m3 to be met by January 2015, and an indicative limit value of 20ug/m3 from January 2020, subject to a review in 2013. The Review of evidence on health aspects of air pollution (REVIHAAP) concluded that there is a “strong need” to at least lower the 20ug/m3 limit.