Londoners and businesses are being asked if a multi-million pound plan for a "low emission zone" should go ahead.
A daily charge for heavy polluting vehicles could be up to £200
Under Mayor Ken Livingstone's plans diesel vehicles such as old lorries, buses and coaches would face a charge to drive into Greater London.
If the scheme - aimed at improving health and helping meet UK and EU air quality targets - receives backing it could be in place by 2008.
Results of the 12-week consultation will be handed to the mayor by summer.
Cars would not be included, nor would vehicles on the M25 London Orbital.
Speaking at City Hall, Mr Livingstone said: "It's a tax on people who trigger premature death.
"If people wish to continue to pollute us to death, they are going to have to pay for the... privilege."
Transport for London (TfL) is considering a daily charge of between £100 and £200 on vehicles which have not been modified to reduce emissions, and between £500 and £1,000 for a penalty charge.
BBC London's political editor Tim Donovan said the mayor wanted to introduce a punitive regime because London has the worst air quality record in the country.
The £130m operation would involve TfL registering 60,000 vehicles, he said.
The mayor, who successfully fought off much opposition to his £8-a-day congestion charge scheme, has said he wants to make London the most environmentally-friendly city in the world.
But it is currently unlikely to meet its targets for reducing nitrogen dioxide and particulate matter - 47% of which is caused by road transport, according to the mayor.