Variations in the concentrations of main air pollutants in London

We determined the main characteristics of variations in concentrations of the main air pollutants, namely, ozone, nitrogen monoxide and dioxide, carbon monoxide, sulfur dioxide, as well as suspended particles in London for the period of 2000–2012. The pollution level in London is comparable to that in Moscow. At daytime, the diurnal behavior of ozone is opposite to those of the primary atmospheric pollutants; their seasonal behaviors are also opposite. This indicates that vertical mixing plays a key role in diurnal and seasonal variations in these pollutants. The “weekend effect” is observed for all air pollutants. Statistical data of episodes with elevated levels of pollutant concentrations are presented. When long-term variations are considered, the levels of the primary atmospheric pollutants (especially SO2 and CO) decrease, while the ozone level is more likely to increase.