Bristol is set to become the first UK city to ban diesel cars in a bid to improve air quality.
Mayor Marvin Rees saying they had a "moral, ecological and legal duty" to cut pollution after the measure was approved by the city council on Tuesday evening.
Under the plans, all privately owned diesel vehicles will be barred from entering a clean air zone in the city centre every day between 7am and 3pm by March 2021.
The proposals are subject to government approval and consultation with local residents and businesses
Mr Rees told the council: "We have a moral, we have an ecological and we have a legal duty to clean up the air we breathe."
Drivers breaking the ban will be fined. Although councillors have considered introducing a £60 penalty, Mr Rees said the size of the fine is yet to be finalised.
Mike Jackson, the council's head of paid services, confirmed: "We haven't decided what the amount of that penalty charge should be
A car scrappage scheme has also been proposed in a bid to encourage road users to switch to less damaging alternatives.
Diesel-powered commercial vehicles like buses, taxis and heavy goods vehicles will also face restrictions but efforts will be made to minimise disruption.
Labour cabinet member for housing Paul Smith referred to a recent Bristol-wide study which found that "at least 300 people a year are dying because of air pollution".
Mr Rees said: "A city is like a big Rubik's Cube - you move one thing, other things come out of kilter. That's why we take the time to think about it and begin to take action."
The decision was not universally popular, with councillors expressing concerns over whether it would become harder to get to hospital.
Conservative councillor Claire Hiscott said people on low incomes could be affected as "if you need to get to the hospital and you have a diesel vehicle you will face a hefty fine if you cross that zone in an emergency."
Critics complained about the decision, one voicing concerns about the impact on businesses, another arguing the move should be delayed to allow new owners of diesels to change.
The Government's Joint Air Quality Unit, made up of officials from the Department for Transport and Defra, is expected to begin reviewing the approved plans on Wednesday.