Speed limits should be reduced to 50mph on some sections of motorways to cut down on air pollution, a health watchdog has said.
Experts at Nice also recommended that speed bumps should be removed so motorists do not create fumes by constantly breaking and accelerating as they drive between them.
New draft guidance for England said some stretches of the motorway should have 50mph speed limits – displayed on overhead signs – to encourage drivers to stay at a constant speed and which could then be relaxed at night when there was little traffic.
Other suggestions include reducing the impact of air pollution include rolling out 20mph zones across built-up areas and extra speed cameras.
Nice also said a review of tree-lined streets was required as tree canopies stop fumes escaping and make the roads below more polluted and that councils should display ‘no-idling’ signs urging drivers not to leave their cars running.
Air pollution causes up to 25,000 deaths a year from heart attacks, strokes, asthma and lung disease, according to Nice.
The health watchdog wants councils to adopt the proposals but they are not legally binding.
Professor Mark Baker, the director for the Centre of Guidelines at Nice, said: "If the traffic is such that you are stopping and starting, decelerating and accelerating, then that increases emissions, pollution and fuel consumption.
"In those circumstances, slowing everything down to 60mph or 50mph is the best approach - but not all the time."
Ralph Bagge, leader of South Bucks District Council and deputy chairman of the guideline committee, added: "Smooth driving reduces emissions and stop-start acceleration and deceleration braking is harmful.
"It is putting out more through the tail pipe but secondly braking is also grinding bits of very fine particulate matter which goes into the atmosphere."
