Comment confused on pollution (Score 1) 73
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Picking a city at random (London), road pollution from all causes (including tailpipe and environmental dust disturbed by passing traffic) is not even 15% of total particulate.
"... road transport is estimated to only contribute 12% towards local levels of PM2.5. Conversely, the largest contributor of PM2.5 in cities is estimated to come from wood and coal heating.10 As a consequence of transport’s significant contribution to NO2 pollution in London, concentrations are generally found to be higher at roadside locations than city background levels. London NO2 data shows that over a 1-year period between August 2018 to July 2019, background NO2 levels averaged 28.4 g/m3, while roadside NO2 levels averaged 44.9 g/m3 (exceeding the UK’s legal annual mean NO2 limit of 40 g/m3).11 Ambient air pollution does not respect boundaries, and while London air pollution is made up of some localized emissions from transport, heating and industry, it also received a large amount of transboundary pollution from outside the city. Research estimates that 75% of London’s particulate matter pollution comes from outside the city, while 18% of London’s ambient NO2 emissions come from outside the city.7 Air pollution in London can also be influenced by seasonal weather factors. For example, colder conditions during winter months and low winds can lead to emissions being trapped near the ground in what is also known as a cold temperature inversion, prolonging and intensifying spells of air pollution. These winter smogs in the UK are also colourfully referred to as ‘pea-soupers’. London’s infamous Great Smog of 1952 took place during four days of the winter month of December (5-9th), and this severe smog episode was caused by emissions from excess coal burning to heat homes, combined with unusually cold temperatures and windless conditions which trapped the smog. It eventually dispersed when the weather changed. More recently, London experienced an intense 4-day smog episode between 12-15 December 1991, where NO2 levels broke records as the highest recorded to date, since monitoring began in 1970.12 Conversely, London’s warmer summer months can lead to summer smog episodes. These are typically caused by nitrogen dioxide reacting with hydrocarbons in sunlight, to form ozone" https://www.iqair.com/us/air-q...