The mayor of London has said “bold action” is needed to tackle air pollution after a new report found it causes a greater risk of Covid-19 hospital admission.

Sadiq Khan, who commissioned the review carried out by Imperial College London, said decisions made to eradicate toxic air are now “a matter of life and death”.

The research said long-term exposure to air pollution before the pandemic increased the risk of a person becoming sicker if they became infected with the Covid-19 and being admitted to hospital.

It also said exposure could increase a person’s likelihood of catching the virus, although studies into this effect are still in early stages.

Mr Khan said he remains committed to expanding the ultra-low emission zone (ULEZ) next month, saying: “We cannot turn a blind eye to the clear evidence showing the dangers of toxic air pollution.

“We already know that air pollution is linked to life-changing illnesses, such as cancer, lung disease and asthma. But until now previous studies have underestimated the role air pollution plays in infectious diseases like pneumonia, bronchitis and, most recently, Covid-19.

“This new review led by Imperial researchers makes it crystal clear that tackling air pollution is a vital part of building our resilience to Covid-19, and other infections like it. The decisions we make now to tackle air pollution are truly a matter of life and death.

“That’s why I’m committed to expanding the ultra-low emission zone next month and why I will continue to take the bold action necessary to eradicate pollution from our city.”

Imperial’s environmental research group, a leading provider of air quality information and research in the UK, and the University of Cambridge MRC toxicology unit came to their conclusions after evaluating studies from across the world.

In the last year hundreds of studies into the links between air pollution and Covid-19 have been published, including research by scientists in the US linking smoke from the recent devastating wildfires with an increase in hospital admissions and deaths from the virus.

Imperial’s report said there is evidence that increased exposure to fine particulate matter is related to increased hospital admissions in those with Covid-19.

However, it said while there is some support for links between long-term exposure and worse health outcomes in those who have caught the virus, results may have other explanations.

Researchers also said studies showing air pollution could increase the likelihood of infection are still at an early stage.

The report said: “Air pollution is known to increase amounts or severity of respiratory or cardiovascular disease, and these diseases in turn are known to increase susceptibility to having more severe Covid-19. There are established biological mechanisms for the link between air pollution and disease in general.

“Whilst this study highlights that more research is needed in this area, it is already clear that tackling air pollution is important in reducing the vulnerability of the population to Covid-19, and other infections like it.”

The central London ULEZ is said to have reduced nitrogen dioxide roadside concentrations by nearly a half.

The number of state schools located in areas exceeding legal limits has reduced from 455 in 2016 to 14 as of Monday.

The ULEZ is set to be expanded up to the North and South Circular on October 25, the cost of which could reach £130 million.

Mr Khan has faced criticism over the impact the £12-a-day ULEZ fee and congestion charge – which was raised last June to £15 – is having on businesses.

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