Experts have concluded that there are around 380 deaths a year linked to air pollution from transport in the capital - 150 more than die in road accidents.
Their report, commissioned by the NHS Executive in London and backed by the Greater London Authority also concludes that transport-related pollution puts another 1,200 people in hospital every year.
Minor breathing problems due to exhaust fumes could affect as many as half a million.
The report, On the Move, claims that air pollution is responsible for the deaths of one in a hundred Londoners.
Particle emissions can cause breathing and heart problems and have also been linked to increased risk of developing certain forms of cancer.
London Mayor, Ken Livingstone, said: "This report shows it's more harmful to walk down the street than to cross it."
Solving transport problems is one of the priorities of the GLA and London Health Commission, an umbrella group of agencies, aiming to improve health in the city.
Noise pollution
And it is not just pollution from exhausts which is damaging people's health in the capital.
The new report also points to major problems with noise pollution from traffic, trains and aircraft, which disturbs sleep and affects school work.
"It can be concluded that a very large number of people in London (more than several hundred thousand) are exposed to noise levels above the WHO environmental guidelines," it states
In addition, the report points to the proven health benefits of physical activity such as cycling and walking.
The NHS Executive is planning to undertake further work into developing a framework so that all transport policy decisions are assessed for their implications on the health of local people.
Areas which will be further investigated include speed restriction zones, congestion charging, home zones and new public transport links.