Air pollution lower in UK’s cities despite a return to almost normal traffic levels

Air pollution is lower than expected in some of the UK’s towns and cities, despite a return to almost normal traffic levels, new research shows.

New research conducted by the University of York shows that pollutants such as nitrogen dioxide (NO2) are still lower than expected as the country starts relaxing its lockdown rules.

The findings suggest that the reason for lower air pollution levels are due to staggered commutes and homeworking, both of which reduce congestion – which plays a key role in air pollution.

Dr. David Carslaw from the Department of Chemistry at the University of York said: “Things are not back to normal according to the air quality data. It seems that while traffic levels look lik they have mostly returned to normal; concentrations of some air pollutants are still quite a lot lower than expected. We think the reason is that congestion has not fully retuned, and this has quite a large effect on emissions and hence concentrations.”

The research focuses on NO2, a key pollutant that is caused by vehicles.

Dr. Carslaw and his team have been analysing data from more than 100 sites across the UK as part of ongoing research into concentrations of roadside air pollutants. They have been analysing data throughout lockdown.

The research concludes that at the height of lockdown NO2 levels throughout the UK were 56 percent lower than average. As of 1 July, with many restrictions currently lifted, the levels remain roughly 30 percent lower than average. At the height of lockdown, NO2 levels in York were 52 percent lower than normal, and as of 1 July, they remain about 18 percent lower.

Dr. Carslaw said: “The data across the UK showed a deep plunge after lockdown for concentrations of nitrogen dioxide of around 50 percent on average nationally and a slower recovery.”

Measuring the impact of congestion on air pollution is challenging “as there are many factors that affect emissions,” said Dr. Carslaw.

However, this research is very important as “the analysis of data gathered during lockdown and coming out of lockdown might give researchers an opportunity to better understand more about linkages between air pollution and congestion,” he said.