- Video report by ITV News Political Correspondent Emily Morgan
The sale of new diesel and petrol cars and vans will be banned in the UK from 2040.
The government announced the deadline as part of £3 billion plans to cut illegal levels of air pollution that include scrappage schemes and potential "clean air zones" that could see charges for heavy polluting vehicles.
Environment Secretary Michael Gove said the government wanted to help the car industry "do the right thing".
But campaigners say the 2040 date is too long to wait for clean-air measures that should be brought in far sooner, with other countries - including Germany and India - considering bans by 2030.
Why has the deadline been announced now?
The government was ordered to produce new plans to tackle illegal levels of harmful pollutant nitrogen dioxide - with diesel and petrol vehicles prime contributors.
The High Court had agreed with environmental campaigners that a previous set of plans would fail to meet EU pollution limits and ordered a rethink.
The government tried to delay the publishing until after the General Election before being forced to set out the draft plans in May, with the final measures for the clean air strategy due by July 31.
The government has published them just days before the deadline.
Is the shift to electric vehicles accelerating?
On Tuesday, BMW announced plans for an electric Mini to be assembled at its Oxford plant, while earlier this month Volvo unveiled its moves towards cleaner cars.
Many manufacturers have accelerated their testing and increased investment in all-electric or hybrid vehicles as the industry makes the long-term move away from its traditional but high-polluting power sources.
Mr Gove said: "The good news is that the car industry is already moving in this direction ... it's critically important that we provide the encouragement from government to help the car industry do the right thing."
The government's strategy follows similar plans announced in France this month to drive towards cleaner vehicles and less-polluted public air.
What are the other new clean air measures?
The £3 billion strategy includes a pledge of £255 million funding to help councils speed up local measures to deal with pollution from diesel vehicles.
These could include "targeted" diesel scrappage schemes, changes to road layouts, and "clean air zones" which charge the dirtiest vehicles.
Ministers want to retrofit buses and other transport while altering speed humps and re-programming traffic lights to make traffic flow more smoothly to reduce pollution.
So will drivers be charged for a heavy polluting vehicle?
Campaigner calls for charging zones were supported by an assessment published alongside the draft plans that suggested they were the most effective measures to tackle nitrogen dioxide, much of which comes from diesel vehicles.
However Environment Secretary Mr Gove said he did not believe charges were necessary.
Ministers have been wary of being seen to "punish" drivers of diesel cars, who they claim bought the vehicles in good faith.
"Diesel drivers are not to blame and, to help them switch to cleaner vehicles, the government will consult on a targeted scrappage scheme," a government spokesman said.
Have environment and health campaigners endorsed the plans?
While a deadline to ban diesel and petrol was welcomed, campaigners said 2040 is "far too late" to wait.
Greenpeace UK's Areeba Hamid said Germany, India, the Netherlands and Norway are all considering bans by 2030 or sooner while car manufacturers are moving away from petrol and diesel this decade.
"The UK has the potential to lead the world in clean transport revolution, but it is vital we stay ahead now through a more ambitious phase-out date to boost our domestic market, as other countries are catching up," she said.
The chief executive of the British Lung Foundation, Dr Penny Woods, welcomed more money for local authorities and said the petrol/diesel ban was "ambitious but credible action in the short term will be required".
She added: "This means more new clean air zones that keep the most polluting vehicles off roads and a fair diesel scrappage scheme."
What is the political reaction to the plans?
Green Party MP Caroline Lucas agreed the action "doesn't go nearly far enough or fast enough" to tackle the "health emergency in the coming months and years".
She said government must expand clean air zones and pay for the diesel scrappage scheme, while revamping cities to promote walking and cycling and making public transport "affordable and reliable".
Shadow environment secretary Sue Hayman said the government had only acted because of the demands of the court.
She said the strategy amounted to "further consultations and delays" and condemned the government's "squeamish" attitude to clean air zones which she said shunted the problem on to local authorities.
She said the plans provided no detail on how the 2040 target will be achieved, adding: "With nearly 40 million people living in areas with illegal levels of air pollution, action is needed now, not in 23 years' time."
What has the government said in response?
A spokesman said the government is "determined to take strong action in the shortest time possible" to battle poor air quality that it said is the biggest environmental risk to public health in the UK.
"That is why we are providing councils with new funding to accelerate development of local plans, as part of an ambitious £3 billion programme to clean up dirty air around our roads," he said.
"Our plan to deal with dirty diesels will help councils clean up emissions hotspots - often a single road - through common sense measures which do not unfairly penalise ordinary working people."
Where are some of England's most polluted roads?
More than 80 A-roads and motorways in England breach legal EU limits for air pollution, the Department of Environment, Food and Rural Affairs says.
More than half of these are in London, including parts of the A1, the North Circular, the A2 in the east of the capital and the M4.
Roads outside of London which breach legal limits include:
- A35 in Southampton and New Forest
- A3024 in Southampton
- M27 in Test Valley
- A38, A4540, A452 and A4400 in Birmingham
- A4053 in Coventry
- A52 in both Derby and Nottingham
- A601 in Derby
- A6514 in Nottingham
- M60 and A635 in Manchester and Tameside
- A5103, A57(M) A57 and M56 in Manchester
- A34 in Stockport
- A58 in Bury
- A666 in Bolton
South and West Yorkshire
- A630 in Sheffield and Rotherham
- A57 in Sheffield
- A58, A643, A61, A58(M) and M621 in Leeds
- A1 and A167 in Gateshead and Newcastle
- A1058 in North Tyneside
- A66 in Middlesbrough