Air pollution levels vary greatly between different places in a city. This is the finding of a new study which concludes that trees contribute to cleaner air in cities.

That green spaces can improve the quality of life and create a better climate in our cities is well known, but how important is vegetation for producing cleaner city air? This question is the focus of an extensive collaborative project led by researchers at University of Gothenburg.

In the project’s first study, the researchers measured pollutants in the air and compared them with pollutants on the leaves of deciduous (broadleaf) trees. The study looked at the pin oak (Quercus palustris), and sampling was made in June and September 2018. The study was conducted in seven urban settings in Gothenburg. The researchers chose to focus on PAHs, a group of air pollutants not yet studied closely but some of which are believed to be very harmful to human health.

The trees’ leaves absorb the pollutants

The results are clear: the pollutants in the leaves increased over time and the researchers could show a clear correlation between the level of air pollutants and the concentration of pollutants in the leaves.

«The study establishes that the leaves collect the air pollutants during the summer, thus reducing human exposure to harmful substances in the air. These types of extensive measurements of pollutants in both vegetation and the air are unusual, and the study confirms that trees play a role in improving air quality in cities,» says Hakan Pleijel, professor of environmental sciences at the University of Gothenburg University.

Story Source:
Materials provided by University of Gothenburg. Original written by Ulrika Ernstrom. Note: Content may be edited for style and length.