In May 2019 researchers from China published the results of their study to assess air pollution removal by vegetation planted in cities. It is known that fine particulate matter (PM2.5) can pose health problems for humans and that vegetation can be an effective long-term measure to get rid of air pollution. Various studies have assessed PM2.5 removal by vegetation in cities, but results have been variable and future scenarios have not been well documented. A method of improving these assessments was therefore developed and combined with the vertical distribution of vegetation in Shenzhen City, China. Results indicated that the PM2.5 removal by urban vegetation in 2015 was 1000.1 tons. This gave a maximum hourly local air quality improvement of up to 3%, which differed significantly with elevation. In terms of vegetation type, evergreen shrubs, evergreen broadleaved forests, and evergreen needle-leaved forests had the highest removal efficiency. Based on their results, the researchers believe that an increase in evergreen shrubs in an urban area (at a height of under 100m) would have the best removal potential.
Wu J et al. Using the modified i-Tree Eco model to quantify air pollution removal by urban vegetation. Sci Total Environ. 2019 May 30;688:673-683