Mr Khan will be speaking at a summit on clean air and health in the capital, which will also hear from government's chief medical officer Professor Chris Whitty and Rosamund Adoo-Kissi-Debrah, whose Ella died after a fatal asthma attack.

The nine year old, who lived by the South Circular in Lewisham, was the first person in the UK to have air pollution listed as a cause of death.

The coroner's report, published last year, urged government, the NHS and health and care professionals to do more to inform communities of the serious health effects of air pollution, which will be discussed at the summit.

Mr Khan will say we are facing a "pivotal moment" in efforts to tackle the triple health and economic dangers of toxic air pollution, climate change and congestion.

"We simply don't have time to waste - deadly air pollution is permanently damaging the lungs of young Londoners and affecting older people who are more vulnerable to the impacts of poor air quality," the mayor is expected to tell the summit.

The talks are due to review pollution alerts systems and developing guidance for doctors and nurses to help them talk though air pollution risks with their patients.

Victoria Rance, a campaigner who opposes the £2bn Silvertown Tunnel plans, welcomed efforts to clean up London's air but said it needed to include reduced road use for polluting vehicles, including expanding cycle routes and swapping HGVs for cargo bikes for deliveries.

"The Silvertown Tunnel, a new motorway with HGV lanes and no cycling, which is taking 20-30,000 vehicles into London poorest, most diverse and most polluted borough is a travesty."

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London's air pollution has plunged since Mr Khan became mayor in 2016, according to research by Kings College London published by the Greater London Authority.

City Hall is also publishing updated air quality guides for local authorities, detailing air pollution levels in each borough, especially around priority areas such as schools, hospitals and care homes, and data on health impacts.

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