Lockdown measures in London, which have in turn cut traffic on its roads, have led to "dramatic improvements" in the city's air quality, according to information published by the Mayor of London.
In an announcement on Thursday, authorities said there had been "huge reductions" in nitrogen dioxide (NO2) in the city, "especially at roadside sites."
London's Oxford Street, usually a hub of activity, has seen its daily average NO2 drop by 47%, while Marylebone Road – one of the U.K. capital's busiest roads – had posted a 48% reduction.
U.K. Prime Minister Boris Johnson announced a number of strict measures designed to tackle the coronavirus pandemic on March 23. The government said that people should only leave their homes for certain activities, such as exercise and shopping for necessities. Traveling for work is allowed, but only if that work can't be done from home.
According to the Mayor's office, even before the introduction of measures to tackle Covid-19, hourly average levels of NO2 at central London's monitoring sites had fallen by 35% in 2020 compared to the same timeframe in 2017. Since March 16, a further drop of 27% has been recorded.
"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," Sadiq Khan, the Mayor of London, said in a statement.
"But this cleaner air should not just be temporary, as Londoners deserve clean air at all times," Khan continued.
"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 we've made" through policies such as the Ultra Low Emission Zone (ULEZ) continue.
The ULEZ was introduced to London in April 2019. Designed to operate 24 hours a day, seven days a week, it was temporarily suspended in March in order to allow "critical workers" to travel around the city "as easily as possible" during the coronavirus pandemic.
Around the world, many cities have seen air quality improve since the introduction of lockdown measures. And while the new NO2 figures for London may be heartening, one air quality expert has warned there is still work to do.
"Nitrogen dioxide pollution has gone down, but London recently saw huge spikes in dangerous particulate pollution," Elizabeth Fonseca, from the Environmental Defense Fund Europe, said in a statement issued on the Mayor of London's website.
"A few weeks or months' improvement of just one pollutant doesn't make lung disease and other ailments disappear," Fonseca added.