Among ongoing efforts to combat record levels of pollution, Highways England is considering a proposal to build cantilevered canopies over the most polluted sections of motorways to prevent residents from inhaling the toxic fumes.

A similar idea was trialled in 2015, in which a four-meter (13-foot) barrier was constructed along 100 meters (238 feet) of highway outside of Manchester. Now, Highways England is testing materials that could clean the air. The trial uses a three meter-high fence coated in a mineral polymer material intended to absorb nitrogen dioxide. It is hoped that the final product will cut emission fumes and improve air quality.

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Pollution is linked to 40,000 premature deaths each year in the U.K., and 500,000 a year in the EU as a whole. Governments across the EU have had transport, the biggest source of harmful emissions, in their sights since Volkswagen’s diesel scandal revealed that actual levels of emissions were much higher than automakers had alleged. As part of the U.K.’s bid to improve air quality, Highways England has been given 100 million pounds ($132.35 million) to develop a clean air plan through 2021. The “pollution tunnel” is part of their proposed strategy of how they will use these funds.

That plan also includes a target of putting charging stations for electric cars every 20 miles on 95% of the roads. The plan will also involve a pollution tax on new diesel vehicles, with an aim of ending the sale of diesel and gasoline cars by 2040.