Thirty trees in wooden planters have been placed outside four homes on South Road for a two-week experiment. The results will be screened by the BBC later this year.

Professor Barbara Maher of Lancaster University is carrying out the experiments after she was contacted by the BBC following similar research on road pollution which suggested that trees help to absorb vehicle fumes.

Traffic pollution produces minute particles (“particulates”) which are harmful to health but the presence of trees can reduce this significantly.

Levels of particulate pollution inside the houses both with trees outside and without the trees will be measured and compared to find out if the trees make a difference.

Professor Maher said: “These particulates can enter a house through leaky mortar, windows or through ventilation and their levels will rise during the morning and evening rush hours. Trees can do a good job of intercepting some of these particulates so we will take samples from the TV screens inside the houses which collect a particulate sample for us. Wind and rain do tend to blow or wash away particulates so the indoor results are dependent on the weather.

"We also need to remember that houses also contain air pollution from other sources – people smoking or cooking fatty foods, and from fire retardants on furniture.”