Gridlocked Hammersmith and Fulham is carrying 10,000 or more cars a day on 18 of its roads, figures have revealed.
The survey was carried out as new research in the British Medical Journal found prolonged exposure to traffic fumes, which contain nitrogen dioxide, can increase risk of a heart attack.
More than 1,700 of the capital's roads carry at least 10,000 vehicles a day, with many producing levels of pollution more than double the legal limit. Borough streets affected are:
Putney Bridge Road, Fulham High Street, Wandsworth Bridge Road, Fulham Palace Road, Fulham Road, Lillie Road, Old Brompton Road, Talgarth Road, Hammersmith Bridge Road, King Street, Glenthorne Road, Western Avenue, Goldhawk Road, Hammersmith Flyover, Scrubs Lane, Wood Lane, Shepherd's Bush Road and Shepherd's Bush Green.
The research comes as Hammersmith and Fulham Council builds a new slipway in Fulham Palace Road, which the authority says will ease congestion. Opponents, however, think the scheme is un-green.
The government has admitted the capital will not be able to meet European legal limits for traffic until 2025, prompting London Assembly Green Party member Darren Johnson to question whether enough is being done to combat the problem.
He said: "By abandoning any attempt to meet the European deadlines for action on air pollution, the government is giving up on Londoners’ health. Why should Londoner’s suffer air pollution longer than anywhere else in the country? The Mayor of London can’t just shrug his shoulders and regret the impact on Londoner’s health of Government inaction. We need the Mayor to get a grip on the problem by putting a new set of actions in place. That means rewriting his air pollution strategy and making traffic reduction his number one priority."
Mr Johnson has recently backed a new measure to get taxi and bus drivers to switch the engines off while stuck in traffic and has been praised for introducing the cycle hire scheme.
"Pollution is a serious health issue and Boris Johnson is determined to reduce its impact," said Kulveer Ranger, the Mayor's environment director.
