NO2 has a clear local pattern and is mostly concentrated where it is emitted: in urban areas and by busy roads. NO2 values are particularly high in the areas around London, but all urban areas have high levels.
PM2.5, which includes soot and dust generated by the burning of fuels and from brake pads being applied to tyres, is more widely spread. Despite this there is still a clear geography — levels are higher in cities than their surrounding areas, and particularly high in cities in the Greater South East.
7 The higher levels seen across the Greater South East as a whole result partly from emissions from London and from contributions from continental Europe.