Olympic chiefs are being urged to investigate whether London is meeting air quality regulations.
Green Party members on the London Assembly warned that air pollution in the capital could prevent it meeting key conditions for hosting the 2012 Games.
They want the International Olympic Committee (OIC) to assess whether the city is breaching the Host City Contract, which requires London to comply with environmental law as it prepares for and hosts the Olympics.
In September, a Green Party report said London's streets were breaching the European Union's legal limits for air pollution.
It said seven sites exceeded daily PM10 limits on more than 35 days in a year - the limit set by EU chiefs - but their figures were called into question by experts.
Darren Johnson, Green Party London Assembly member said: "The Government recently admitted that it is highly unlikely that it will meet targets for reducing nitrogen dioxide, particulate matter and ozone.
"The IOC must investigate whether this would be a breach of the contract signed when London won the bid."
He added: "We must reduce the total amount of traffic already in London, and replace cars with bikes, pedestrians and buses.
"We must scrap developments like the Thames Gateway road bridge and massive car parking, which generates more traffic."
His comments came in the same week that the Commission for a Sustainable London 2012 announced a full team of advisors and launched its 2008 programme.
The Commission, set up to monitor sustainability, planning and progress for the Games, now has 12 expert advisors and is planning four reviews and three progress reports in 2008.
The Olympic Delivery Authority - which is in charge of constructing all the venues - said last year it will champion low waste, low carbon emissions and green transport methods in a bid to make the Olympics the greenest in modern times.
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