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Lockdown has cut pollution levels by as much as half near busy roads in London

Joseph Delves
19 Aug 2020

Study by King's College London shows how quickly air quality could improve if urban traffic were reduced

Levels of nitrogen dioxide (NO2) pollution beside main roads in London fell by as much as 55% during the coronavirus lockdown.

A study by Kings Colledge found that levels adjacent to Marylebone Road and Euston Road were down 55% and 36% respectively. This coincides with a drop in vehicle use across the capital of 53% during the same period.

However, the study found that the reduction was more pronounced in Central London, with less of a decrease in more residential areas. Overall the concentration of NO2 lowered by 21.5% across the capital since the Government introduced lockdown measures.

In urban areas, nitrogen dioxide pollution is mainly due to traffic. Long-term exposure to NO2 decreases lung function and increases the risk of respiratory illness. Its reaction with other forms of pollution, such as particulate matter, also has a knock-on effect in causing other adverse health and environmental outcomes.

'Our early analysis of the lockdown showed significant reductions in nitrogen dioxide (NO2) particularly near busy roads in London where in some central areas concentrations were halved,' explained Professor Martin William, Head of Science Policy and Epidemiology at King’s College London.

While nitrogen dioxide decreased markedly, the study found that during the same time particulate matter increased. This was in part due to the high temperatures and prevailing winds driving it from other areas of Europe.

Much of London is now covered by the Ultra Low Emission Zone. This sees drivers of heavily polluting cars charged £12.50 to enter central areas.

Heavier vehicles, including lorries, are charged at a rate of £100. Since its introduction last year, the number of the worst polluting vehicles on the roads has dropped from 35,600 to 23,000, resulting in a 20% reduction in emissions in Central London.

Despite this, diesel engines continue to be a major contributor to levels of NO2.

A full copy of the report can be found here.