Urban Vegetation and Air Pollution Mitigation

Urban vegetation, encompassing street trees, parks, green roofs, hedges and living walls, offers a passive but multifaceted approach to reducing air pollution. Leaf surfaces and stomata capture particulate matter and absorb gaseous pollutants, while canopy structure and planting configuration influence airflow and pollutant dispersion at micro- and meso-scales. The effectiveness of green infrastructure depends on species-specific traits, local meteorology and urban form, requiring optimisation of plant selection to balance particle deposition, aerodynamic effects and potential emissions of biogenic volatile organic compounds or pollen. Advances in remote sensing, deposition modelling and leaf surface chemistry have refined our understanding of how strategic greening can complement emission control measures, delivering co-benefits for urban heat island mitigation, biodiversity enhancement and public health.

Research from Nature Portfolio

Recent studies have quantified species-level variation in particulate capture by urban trees. Foliar traits such as groove density, trichome abundance and leaf shape significantly influence PM2.5 adherence and retention. Coniferous species with needle-like foliage exhibit higher accumulation per unit area, while certain broadleaved taxa rely on epicuticular wax and micro-roughness. Post-rainfall recapture dynamics reveal that not all retained particles are washed off, with species differences in resuspension rates impacting net deposition. These foundational insights guide urban forestry by identifying tree species with superior biofiltration capacity under variable climatic and pollution regimes.

Urban Vegetation and Air Pollution Mitigation publication trend

The graph below shows the total number of articles in urban vegetation and air pollution mitigation across all publications each year (not limited to Nature Index journals).

Technical terms

Particulate matter (PM2.5, PM10): Airborne particles with aerodynamic diameters below 2.5 µm and 10 µm, respectively, capable of penetrating the respiratory system.

Dry deposition: Direct transfer of airborne pollutants to surfaces via gravitational settling and turbulent transport.

Wet deposition: Removal of pollutants from the atmosphere through precipitation scavenging.

Green infrastructure: Strategically designed vegetation elements—such as trees, hedges, green roofs and living walls—integrated into urban landscapes.

Epicuticular wax: A hydrophobic layer on leaf surfaces that influences pollutant adhesion and retention.

References

1. The Chemical Landscape of Leaf Surfaces and Its Interaction with the Atmosphere. Chemical Reviews (2024).
2. Reassessing the role of urban green space in air pollution control. Proceedings of the National Academy of Sciences of the United States of America (2024).
3. Variation in Tree Species Ability to Capture and Retain Airborne Fine Particulate Matter (PM2.5). Scientific Reports (2017).
4. Designing vegetation barriers for urban air pollution abatement: a practical review for appropriate plant species selection. npj Climate and Atmospheric Science (2020).
5. Using green infrastructure to improve urban air quality (GI4AQ). Ambio (2019).
6. Considerations for evaluating green infrastructure impacts in microscale and macroscale air pollution dispersion models. The Science of The Total Environment (2019).
7. The influence of the vegetation cycle on the mitigation of air pollution by a deciduous roadside hedge. Sustainable Cities and Society (2020).