Drivers of diesel cars are to be given financial help by the Government, Theresa May has hinted, as cities across the UK prepare to introduce new taxes on the vehicles.
Mrs May said she is very conscious of the fact that there was a push towards diesel under Labour more than a decade ago because of concerns over carbon emissions .
Her comments are the clearest indication yet that the Government is considering introducing a scrappage scheme to incentivise drivers to trade-in older diesel vehicles.
Alternatives could include dropping plans to tax diesels entering cities and preventing councils from making diesel drivers pay more to park.
The proposals come as a so-called toxin tax, under which drivers of up to 10 million older diesels facing fees of up to £20 per day to drive into urban areas, is set to be introduced.
Sadiq Khan, the Mayor of London, on Tuesday announced the most punitive levy yet on diesel motorists as he announced plans to charge them £24 a day to drive in central London from 2019. He said: The air in London is lethal and I will not stand by and do nothing.
Speaking to reporters during her tour of the Middle East, Mrs May said a final decision would be taken when the Government publishes a new air quality plan, a requirement under EU laws to reduce pollution.
She said: “Decisions will be taken when we produce that plan … but I’m very conscious of the fact that past governments have encouraged people to buy diesel cars and we need to take that into account when we’re looking at what we do in the future.”
Tory MPs and motoring organisations said that instead of hitting drivers with new taxes, ministers could reduce emissions by removing speed bumps and other traffic-calming measures.
Researchers have found that the level of harmful emissions increases significantly when vehicles slow down and accelerate.
Charlie Elphicke, a Tory MP who is chairman of a cross-party parliamentary group on fuel, said: Instead of punishing drivers with a toxin tax, we could drastically lower emissions by cutting congestion.
Ed King, president of the AA, said: It appears that many local authorities are impeding the flow of traffic with road humps, chicanes, pinch points and poorly managed traffic lights. Cars are much more efficient when they can run at a consistent speed.
Research by Imperial College London found driving over speed bumps in a diesel car produce 98 per cent more nitrogen dioxide than driving over road cushions, prompting calls for them to be removed outside schools.
Ministers are being forced to come up with tougher measures to target diesel drivers after losing a High Court case against environmental campaigners Client Earth.
In London, all but the newest diesel cars will face a £12.50 charge to drive in the planned ultra-low emissions zone (Ulez), which would cover the same central area as the current congestion charge zone.
Under the plans, diesel cars that are more than four years old in 2019 and petrol cars that are more than 13 years old will face the charge 24 hours a day, year-round, in a bid to cut air pollution.
With the congestion charge during weekday hours, the total fee for the most polluting cars to drive through the heart of London would be £24.
The introduction of the Ulez charge for central London is expected to cut emissions of dangerous nitrogen oxides from traffic pollution by almost half by 2020.