Urban trees, air quality and human health

The research paper examines how urban forests influence air quality and public health. It highlights that trees improve air quality by directly removing gaseous pollutants and particulate matter, and indirectly by reducing urban heat island effects and building energy demand. However, it notes that trees can also emit volatile organic compounds (VOCs) and pollen, and may trap pollutants near emission sources like roadways if not designed correctly. The paper concludes that while the overall effect is positive, local forest design is critical to maximize health benefits.

• Urban trees improve air quality and human health by reducing ambient temperatures through shading and evapotranspiration, which in turn lowers the emission of temperature-dependent pollutants and ozone-forming chemicals.
• Trees directly remove air pollutants through stomatal uptake of gases and the interception of particulate matter, though the latter is only temporary as particles can be resuspended or washed away.
• The capacity for pollution removal varies by location and tree cover; one hectare of urban tree cover removes an average of 67 kg of pollution annually, though this can exceed 200 kg in more polluted areas with long growing seasons.
• Urban forests in the conterminous United States provide significant economic and environmental benefits by reducing residential building energy use for heating and cooling by 7.2%, saving approximately $5.4 billion per year and avoiding thousands of tons of power plant emissions valued at $2.7 billion annually.
• Trees can have negative impacts on air quality by emitting volatile organic compounds (VOCs) that contribute to ozone and particulate matter formation, and by producing pollen that triggers allergic reactions.
• Poorly designed urban forests, particularly those near roadways, can increase local pollution concentrations by trapping pollutants beneath canopies or reducing wind speeds and mixing heights.
• The health benefits of tree-mediated pollution removal are quantifiable; for example, trees in the conterminous United States removed 22.4 million tonnes of air pollution in 2010, with health effects valued at $8.5 billion and the avoidance of over 850 human deaths.

APA

GreenLatinos (n.d.). Urban trees, air quality and human health. https://www.greenlatinos.org/wp-content/uploads/2024/09/Nowak_2020_air-pollution-and-trees.pdf

Chicago

GreenLatinos. Urban trees, air quality and human health. n.d. https://www.greenlatinos.org/wp-content/uploads/2024/09/Nowak_2020_air-pollution-and-trees.pdf.

Wikipedia

{{cite report |author=GreenLatinos |title=Urban trees, air quality and human health |url=https://www.greenlatinos.org/wp-content/uploads/2024/09/Nowak_2020_air-pollution-and-trees.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{greenlatinosndurban, author = {{GreenLatinos}}, title = {{Urban trees, air quality and human health}}, institution = {GreenLatinos}, url = {https://www.greenlatinos.org/wp-content/uploads/2024/09/Nowak_2020_air-pollution-and-trees.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }