Trees in cities throughout the United Kingdom are significantly improving the quality of the air we breathe by decreasing pollution levels for pedestrians, according to a recent study.

Researchers from the University of Leicester's Department of Physics and Astronomy found that trees have a regionally beneficial impact by increasing turbulence and reducing ambient concentrations of road traffic emissions -- by 7 percent in Leicester City at pedestrian height on average.

"Predicting the concentration of air pollutants is essential for monitoring air quality in cities. We focused the study on the city center of Leicester where you have a high density of building and traffic," researcher Antoine Jeanjean said in a statement. "Our fears of trees trapping pollution around streets were revealed to be unfounded. In some situation they can increase pollution locally but on average their impact is beneficial in terms of pollutants dispersion."

For the study, researchers focused on the city of Leicester, where up to 90 percent of some atmospheric pollutants such as nitrogen dioxide are emitted by traffic. They looked at ways trees could help to reduce air pollution in cities. To do this, they created a model with aerial mapping company Bluesky based on 3D representation of the city of Leicester with buildings, road and trees databases.

They found that while trees decrease the wind speed over the city, at the same time they produce more turbulence that helps in dispersing the pollution emitted by traffic, resulting in lower exposure for the public.

Researchers also found that while trees decrease the wind speed over the city, at the same time they produce more turbulence that helps in dispersing the pollution emitted by traffic, resulting in lower exposure for the public.

In addition to the increased dispersion of pollution by trees, there are also well known benefits of urban trees such as reduced stress, noise suppression and chemical and physical removal of certain pollutants.

"The study highlights the importance of combining local and regional scale models for assessing the impact of trees in urban planning," Dr. Roland Leigh from the University of Leicester's Department of Physics and Astronomy and a member of the University's Air Quality Group said in a statement.

The findings are detailed in the journal Atmospheric Environment