Elsevier

Atmospheric Environment

Volume 105, March 2015, Pages 130-137
Atmospheric Environment

Review
Review on urban vegetation and particle air pollution – Deposition and dispersion

https://doi.org/10.1016/j.atmosenv.2015.01.052Get rights and content
Under a Creative Commons license
open access

Highlights

  • Combining deposition and dispersion helps designing urban vegetation related to air quality.

  • The dilution of emissions with clean air from aloft is crucial; limit high urban vegetation.

  • High concentrations of air pollutants increase deposition; vegetation should be close to the source.

  • Air floating above, and not through, vegetation barriers is not filtered; decides barrier porosity.

  • Differently designed vegetation catch different particle sizes.

Abstract

Urban vegetation affects air quality through influencing pollutant deposition and dispersion. Both processes are described by many existing models and experiments, on-site and in wind tunnels, focussing e.g. on urban street canyons and crossings or vegetation barriers adjacent to traffic sources. There is an urgent need for well-structured experimental data, including detailed empirical descriptions of parameters that are not the explicit focus of the study.

This review revealed that design and choice of urban vegetation is crucial when using vegetation as an ecosystem service for air quality improvements. The reduced mixing in trafficked street canyons on adding large trees increases local air pollution levels, while low vegetation close to sources can improve air quality by increasing deposition. Filtration vegetation barriers have to be dense enough to offer large deposition surface area and porous enough to allow penetration, instead of deflection of the air stream above the barrier. The choice between tall or short and dense or sparse vegetation determines the effect on air pollution from different sources and different particle sizes.

Keywords

Urban
Air quality
Vegetation
Deposition
Dispersion
Particle size

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