Free-flowing traffic is making it easier to breathe: Air pollution is at 30% of pre-lockdown levels in London and major UK cities because vehicles are spending less time stuck in queues
- Analysis of more than 100 roadside sits found nitrogen dioxide levels were down
- This is despite the return of near-normal traffic levels after easing of lockdown
- Staggered commutes and homeworking cites as factors in reducing congestion
Air pollution is lower than expected in UK town and cities, despite the easing of coronavirus restrictions sparking a return to near-normal traffic levels, new research shows.
Analysis of more than 100 roadside sites across the country by the University of York found nitrogen dioxide (NO2) pollution levels were 30 per cent below normal on July 1 – despite the lifting of many lockdown rules.
At the height of the crisis, NO2 levels were some 56 per cent lower than normal nationwide, the study found.
Graphs show how congestion is down and air is cleaner than usual, despite traffic returning to near-normal levels
Staggered commutes and homeworking are cited as factors in reducing congestion, which potentially contributes to air pollution.
Similarly, TomTom traffic data at the 5pm peak yesterday showed congestion was down 21 per cent from the average level in 2019.
It also showed this week’s average congestion was at 25 per cent, compared to 38 per cent in late February and early March, before lockdown conditions were imposed.
This is despite there now being a similar number of vehicles on the roads as there was before lockdown, with HGV traffic being back at 95 per cent of normal levels, vans at 90 per cent and cars at 75 per cent, according to the Guardian.
Dr David Carslaw, who led the analysis, said: ‘The data across the UK showed a deep plunge after lockdown for concentrations of nitrogen dioxide of around 50 per cent on average nationally and a slower recovery.
‘Things are not back to normal according to the air quality data. It seems that while traffic levels look like they have mostly returned to normal, concentrations of some air pollutants are still quite a lot lower than expected.
TomTom traffic data at the 5pm peak yesterday showed congestion was down 21 per cent from the average level in 2019
‘We think the reason is that congestion has not fully returned, and this has quite a large effect on emissions and hence concentrations.
‘Trying to measure the impact on air pollution of congestion is very challenging as there are so many factors that affect emissions.
‘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.’
NO2, primarily produced by diesel vehicles, has been at illegal levels in many towns and cities for the last decade and is thought to be responsible for some 23,500 early deaths every year.
Dr Carslaw’s colleague at the university, Professor Alastair Lewis, suggested vehicles spending less time idling in queues was a key factor.
‘The relatively modest rebound seen in NO2 is likely a complex mix of smoother flowing traffic and changes in commuting behaviour,’ he told the Times.
‘There may also be some less obvious influences, for example free-flowing traffic induces turbulence in the air and helps mix pollution away, whereas stationary traffic does not.
Traffic was queuing on the M5 last weekend but nitrogen dioxide levels have been 30 per cent below normal even after the easing of lockdown restrictions
‘This is on top of the more obvious effects of repeated stop-starts which are a critical cause of [vehicle] pollution.’
Scientists said last week ‘it would not be surprising’ f there was a link between exposure to air pollution, either past or present, and the number and severity of coronavirus infections.
Given this, it would not be surprising if there was a link between exposure to air pollution – past or present – and the occurrence or severity of COVID-19 infection.
This has previously led lawyers to claim the government has a ‘legal obligation’ to review its strategy on air quality.
A select committee of MPs will also probe delays in cities rolling out clean air zones as a result of the pandemic.
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