England’s busiest freeways could be covered by pollution-absorbing tents to protect nearby homes from exhaust fumes.

Highways England has a £100 million ($131 million) government-provided fund to be used to improve air quality on the highways network by 2021.

It says the unprecedented level of investment is allowing it to conduct trials using a barrier incorporating a new polymer material with the potential to absorb nitrogen dioxide produced by diesel engines.

Highways England, which operates, maintains and improves England’s motorways and major roads, previously has tested paint that absorbs oxides of nitrogen alongside the network.

It began testing an air-quality barrier in 2015 on the M62, a 107-mile (172-km) east-west motorway in northern England connecting Liverpool and Hull via Manchester and Leeds.

The 328-ft. (100-m) barrier, initially 13.1 ft. (4 m) high, was raised to 19.7 ft. (6 m) in early 2016.

“We then progressed to carry out a trial of a barrier incorporating an innovative material with potential to clean the air,” a Highways England report says.

“We are using these trials to investigate if barriers can help contribute to improving air quality for our neighbors. The results from the monitoring of such trials will help us understand if this has been a success with the potential to implement barriers on our network.

“We are also investigating if we can reduce the costs to construct a canopy, which is a tunnel-like structure designed to prevent vehicle emissions reaching our neighbors, to make this a viable solution,” the report says.