Tunnels over motorways could be used as barrier to pollution
Motorways could be covered by tunnels to protect communities from dangerous levels of pollution, Highways England has announced.
Canopies could be built around the busiest roads to soak up car fumes, according to the company's latest air quality strategy.
The document states that Highways England is "investigating if we can reduce the costs to construct a canopy, which is a tunnel-like structure designed to prevent vehicle emissions reaching our neighbours".
After trialling a similar physical barrier to pollution in 2015, which initially stood at four metres high and stretched 100 metres along the M62, it is now running tests on a material that can clean the air.
If this trial proves successful, Highways England said it would consider implementing such barriers across its network of England's motorways and major A-roads.
Air pollution is linked to around 40,000 premature deaths a year in the UK, and transport also accounts for around a quarter of the country's greenhouse gas emissions.
Highways England has been given Â£100 million by the Government to improve air quality through to 2021, and the strategy released sets out how it plans to spend that money.
It includes a target to put a charging point for electric cars every 20 miles on 95% of the road network.
The report also states that diesel HGVs are the biggest contributors to roadside levels of nitrogen dioxide, which causes respiratory diseases.
A Highways England spokesman said: "The best solution to accommodating the extra traffic on our roads without negatively impacting on air quality is cleaner low-emission vehicles.
"In the meantime, we are investing Â£100 million to test new ideas including less-polluting fuels and road barriers which can absorb harmful emissions."
Ministers last week unveiled their court-mandated plans for meeting legal European Union limits on harmful nitrogen dioxide pollution - much of which comes from road transport - after a long-running legal battle.
They include a proposal to fund measures to cut pollution with a tax on new diesel vehicles, and an aim to ban the sale of all conventional petrol and diesel cars by 2040.