The BBC filmed Professor Maher conducting experiments on the A6 in Lancaster to illustrate how trees can help reduce the effects of pollution. Thirty trees in wooden planters were placed outside homes on South Road for a two-week experiment this summer and the results will be screened during the show.

Professor Maher was contacted by the BBC following her research which suggested that trees can reduce the amount of traffic-derived pollution getting into people’s houses.

Traffic pollution produces minute particles (“particulates”) which are harmful to health but particular species of trees can effectively trap many of the particulates and help reduce the health hazard.

Professor Maher said: “It was great that the BBC provided the means to carry out the tree experiment, both to raise people’s awareness of the health hazard of traffic-derived particulates, and to see just how effective roadside trees can be in reducing the problem.”

Levels of particulate pollution inside the houses both with trees outside and without the trees were measured and compared to find out how much of a difference the trees could make.