Figures published by the Mayor of London on Thursday show that nitrogen dioxide (NO2) levels in some of the city’s busiest roads are almost half what they were before lockdown.
The new figures show that central London roadside locations have seen a fall in daily average NO2 of around 40 per cent.
One of Londons busiest roads, Marylebone Road, has seen a reduction in daily average NO2 of 48 per cent while Oxford Street has seen a reduction of 47 per cent, City Hall says.
The new report also matches preliminary analysis by experts at the University of York which shows that levels have dropped by more than 40 per cent in a number of UK cities in recent weeks.
But despite the improvements, London has still had particulate pollution episodes during lockdown, the report shows.
This shows Londons poor air quality is not just the result of traffic pollution and so further action is required on other sources, including domestic burning and agricultural emissions, it adds.
Mayor Sadiq Khan said: “London has one of the most advanced air quality monitoring networks in the world, which has recorded how the coronavirus lockdown has dramatically improved air quality in London.
“But this cleaner air should not just be temporary as Londoners deserve clean air at all times.
“So, once the current emergency has passed and we start to recover, our challenge will be to eradicate air pollution permanently and ensure the gains weve made through policies such as ULEZ (ultra-low emissions zone) continue.
“It is critical that Government keeps this in mind as part of the countrys recovery from the pandemic.”
Mr Khan claimed air quality in London had already been boosted by measures such as the introduction of a pollution charge through the Ultra Low Emission Zone (Ulez) 12 months ago.
Before the lockdown began last month, hourly average levels of NO2 at monitoring sites in central London were 35 per cent lower compared with the same period in 2017.
Since March 16 there has been a further reduction of 27 per cent.
Meanwhile, Royal College of Physician Special Adviser on Air Quality, Professor Stephen Holgate, said: “A year ago who would have believed our lifestyles would have changed so dramatically? Who would have believed it possible that the toxic air pollution in our capital city would be cut by half as a result of ULEZ and a drastic decrease in travel?
“While COVID-19 has wreaked havoc in our lives, this dreadful virus has brought the importance of outdoor space and the environment into focus.
“The consequences of this virus will be significant and felt for many years to come. However, as peoples behaviours have changed, we have seen real improvements in air quality.
“Were all looking forward to the time when the lockdown is lifted, and once it does, I sincerely hope well be able to retain some of the new cleaner and greener habits weve developed.”
Last month, experts said that air pollution in UK cities is falling as the country went into coronavirus lockdown.
The decrease in pollutants mirrors what has happened in other parts of the world.