Air pollution by ozone across Europe during summer 2009

Ozone levels during summer 2009 were as low as during summer 2008 and according to several indicators were among the lowest since reporting of Europe-wide data commenced in 1997. In contrast to previous summers, in 2009 there were no pan-European multi-day episodes. Summer 2009 was characterised by ozone episodes of two to five days followed by spells with few exceedances. A typical episode usually contained approximately 7-13 % of the total number of exceedances of the information threshold experienced during the summer.