Planting trees is a cost-effective way to tackle urban air pollution, which is a growing problem for many cities.
A study by US-based The Nature Conservancy (TNC) reported than the average reduction of particulate matter near a tree was between 7% and 24%.
Particulate matter (PM) is microscopic particles that become trapped in the lungs of people breathing polluted air.
PM pollution could claim an estimated 6.2 million lives each year by 2050, the study suggests.
Lead author Rob McDonald said that city trees were already providing a lot of benefits to people living in urban areas.