London Mayor Sadiq Khan announced plans to crack down on air pollution, saying his own adult-onset asthma has increased his commitment to tackle a problem that accounts for the premature deaths of almost 10,000 people in the British capital each year.

Khan, who was elected last week, plans to extend London's "Ultra-Low Emission Zone" to include the North and South Circular roads, increase the congestion charge in central London for the most polluting vehicles and give the green light to a Transport for London program to scrap diesel vehicles.

"I know from personal experience that the city's air is damaging people's health as I only recently started suffering from asthma as an adult," Khan said Friday in an emailed statement. "In the past, London has only responded after an emergency, like with the Clean Air Act, which followed the great London smogs of the 1950s. But I want to act before an emergency, which is why we need big, bold and sometimes difficult policies if London is to match the scale of the challenge."

The United Kingdom has long struggled to clean up the air in its cities and faces legal action demanding an acceleration of plans to rein in dangerous pollutants. A World Health Organization report on Thursday said London was among 41 out of 52 U.K. towns and cities monitored that breaches safe levels of so-called PM10 particles, and one of 11 that fails to meet standards on even smaller PM2.5 particles. The pollution has been linked to cancers, heart disease and respiratory problems such as asthma.

"This is a hugely positive announcement from the new mayor and shows clear ambition to clean up London's dirty air," said Alan Andrews, a lawyer at ClientEarth, the London-based environmental law organization that's suing the government over its air quality. "We welcome his plans to extend the Ultra-Low Emission Zone and to bring it in earlier. This is vital if we are to take the dirtiest vehicles out of London."

Khan, who asked for feedback to his proposals, said TFL, the capital's transport agency, will "lead by example" by adopting strict emissions standards for double-decker buses earlier than scheduled, using the cleanest vehicles in pollution hot-spots and buying only hybrid or zero-emission buses from 2018.

He cited research by the Environmental Research Group at King's College London, published last year, which found that Nitrogen Oxide and pollutant particles in the air resulted in the loss of 140,743 "life-years" for Londoners, equivalent to 9,416 premature deaths in 2010.

London has worse air pollution than Berlin, Chicago and Paris, according to a report commissioned by the Greater London Authority. Paris this week started banning cars along its Champs-Elysees on the first Sunday of every month, while vehicles in Berlin must carry colored stickers showing the pollution class they belong to. Only vehicles meeting certain pollution standards may drive in the designated environmental area.

Khan was accused this week of backtracking on his pledge to be London's greenest Mayor, after withdrawing a key obstacle to the expansion of London City Airport. He dropped the Greater London Authority's objection to the airport's planned purchase of land that it will need for the expansion, if the proposal is approved by the government later this year. Sian Berry, a Green Party London Assembly Member, described the move as "a terrible decision."