Tropospheric Ozone and Urban Air Quality

Exposure to air pollution represents a serious problem in many cities all over the world. Despite the achievements in the reduction of traditional emissions (SO₂ and Particulate Matter), the majority of European cities still exceed air quality guidelines. Nowadays, photochemical air pollution causes most of the concern, and in this context attention is focused on ozone — as the most prominent photooxidant — and nitrogen dioxide (NO₂). According to the recent report Air Pollution in Europe 1997 of the European Environment Agency, the EU ozone threshold value for the protection of human health (110 μg/m3, 8 h average) is exceeded substantially (Jol and Kielland, 1997). Based on measurements at urban stations it was concluded that 80 % of the EU urban population is exposed to these exceedances.