Levels of polluting nitrogen dioxide in London have fallen by more than half in some places because of less traffic on the roads during lockdown.
However, levels of tiny polluting particles known as PM10 and PM2.5 have risen to their highest levels this year after being brought in, as easterly winds carried pollutants from northern Europe.
Research from King’s College London found concentrations of nitrogen dioxide, which largely comes from burning diesel and petrol in vehicle engines, have come down by as much as 55 per cent due to a fall in traffic on the road.
The normally busy Marylebone Road saw levels of nitrogen dioxide fall by that amount and concentrations of the pollutant was down more than a third on the Euston Road.
The average hourly concentrations of the pollutant have fallen more than a fifth across the capital.
Professor Martin Williams, head of science policy and epidemiology team at King’s College London, said: “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.
“However, the lockdown period coincided with easterly winds and higher temperatures, so we saw increased particle concentrations (PM2.5) as pollutants from northern Europe added to UK emissions to give higher than usual PM2.5 levels.
“The higher temperatures post lockdown also led to higher ozone concentrations.”
Prof Williams said that, in normal circumstances, the fall in nitrogen dioxide would be beneficial, but that has been masked by increased PM2.5 and ozone levels.
“It also remains to be seen how air pollution affects those with Covid-19. More research is needed to assess how air pollution affects health during lockdown and the role of air pollutants in the spread of the virus,” he said.
Air pollution leads to an estimated 40,000 early deaths in the UK each year, contributing to heart disease, strokes, lung diseases and cancer, and can harm children’s development and may even increase
the risk of dementia.
