Air pollution in the capital may have contributed to the deaths of about 3,000 people in 2005, a London Assembly report has warned.
The city's air quality is well below EU targets and is having a "severe impact" on the NHS, the London Assembly's Environment Committee said.
The research also found that emissions from diesel vehicles remains the main source of pollution.
It urged the mayor to take more "bold action" on the issue.
It recommends that Boris Johnson looks into the feasibility of running the city's public transport system on biofuels to help cut down on harmful emissions.
Displaying "real time pollution levels" in public areas would also give Londoners more information about air pollution levels in their areas, the research said.
"Despite action at borough, regional and national level, the capital is still failing to meet air quality targets," said Darren Johnson, the committee's chairman.
"Reducing air pollution is not just about improving the environment in some abstract way. Our report shows that it's about saving lives."
Harmful emissions contribute to a range of health problems, from coughing and sneezing to more serious illnesses requiring hospital admissions death.
Children and the elderly are worst affected, the report found.