News > High Level of Air Pollution
London and southeastern England are experiencing high levels of air pollution this week. This is due to a combination of local emissions, light winds, pollution from the continent and dust blown over from the Sahara. Southerly winds in the upper levels of the atmosphere have transported Saharan dust hundreds of miles north towards the UK. This has combined with a southeasterly flow at middle levels of the atmosphere drawing in industrial pollution from the continent together with light winds and high pressure that has capped the atmosphere preventing our own local emissions from being dispersed. This mixture has led to some of the highest levels of pollution in parts of England.
Defra issues air pollution warnings which have a 10-point scale for measuring air quality - with level one implying a "low" risk of air pollution and 10 warning of "very high" levels. Levels are determined by the concentration of five pollutants in the air, including NO2, sulphur dioxide (SO2) and ozone. High levels of air pollution are usually reached about five times a year. On Tuesday 1 April, pollution levels hit the maximum of 10 in northwest Norfolk. The Met Office monitors air pollution on a daily basis. Click here to look up London’s air quality forecast, but you can also type in a location near you. You can find out more about the daily air quality index and how to use it here.