Pollution removal is only one of various ways that urban trees affect air quality. Integrated studies of tree effects on air pollution reveal that management of urban tree canopy cover could be a viable strategy to improve air quality and help meet clean air standards.
Nowak, D; Crane, D; Stevens, J.
Urban Forestry & Urban Greening,4(3-4), April 2006, pp. 115-123
Pollution removal (03, PM10, NO2, SO2, CO) varied among cities with total annual air pollution removal
by US urban trees estimated at 71 1,000 metric tons ($3.8 billion value).