A UK highways agency is considering covering motorways by "pollution tunnels" to shield homes from vehicle emissions in a radical plan to improve air quality.
Highways England said this week that it was considering building tents made from pollution-absorbing materials over the busiest highways to protect local residents.
The agency said it was working on trials using a material that had the potential to absorb nitrogen dioxide (NO2), which is produced by diesel engines and causes lung disease, The Times reported.
Tunnels have been used to mitigate noise from highways elsewhere in Europe, such as in Croatia (pictured), and pollution tunnels have been installed in the Netherlands, reports The Times, but this would be a first for the UK.
According to the newspaper, highways officials are working with the Dutch authorities on a design for English roads.
In an air quality plan published 2 August, the agency said it if it was deemed financially viable, the system could involve full tunnels to provide better protection to the public.
Motorists’ association the RAC Foundation criticised the idea, saying tunnels would trap emissions, making air quality worse for drivers and their passengers.
"Concentrating emissions in an enclosed environment is the worst thing you can do for people’s health," said Steve Gooding, director of the RAC Foundation, The Times reported. "In the time it takes to get this scheme off the ground we would hope the car fleet will have been significantly cleaned up."
In a press release Gooding said: "Clearly those clever engineers at Highways England are straining every sinew to improve air quality but this appears to be ‘blue sky thinking’ at its extreme.
"The idea of having a canopy appears to be more about containing the problem rather than solving it.
"What we need to see is accelerated ‘greening’ of the fleet, starting with the trucks, where retro-fitting is an option, and moving rapidly to vans, where we need to see alternatives to the traditional diesel coming to market."
The Highways England plan, which includes other initiatives, comes a week after the government said it would institute a ban on the sale of new diesel and petrol vehicles by 2040.
The government has identified 81 stretches of road where urgent action was needed to prevent illegally high levels of pollution. These include the M60 in Greater Manchester, the M621 in Leeds, the A1 past Newcastle, the A35 in Southampton, the M32 into Bristol and the M4 near Heathrow.
Highways England, which has been given £100 million to tackle pollution between 2015 and 2021, admitted that "emissions from diesel vehicles are a significant contributor to the poor air quality at the roadside".
The agency has been trialling pollution barriers since 2015, when engineers built a 4m high wooden pollution barrier along a 100m stretch of the M62 near Simister, later extending it to 6m.
Image: A section of A7 motorway in Croatia is enclosed by noise barriers and solar panels (Lusaga/CC 3.0)