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

Abstract

h i g h l i g h t sCombining 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. a b s t r a c tUrban 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.

Sand and Dust Storms: Impact Mitigation

“…In urban landscapes, increasing vegetation cover is a long-term measure that is likely to help reduce the health problems associated with atmospheric PM 10 and PM 2.5 concentrations as well as biological and chemical aspects of pollution [123]. Green vegetation has the potential to reduce pollutants through filtration [124], while also regulating microclimatic conditions in a way that offers at least perceived benefits and well-being [125].…”

Approaches to Outdoor Thermal Comfort Thresholds through Public Space Design: A Review

“…In addition to these review articles, other reviews of the state-of-the-art with a slightly different perspective have also been disseminated, namely the (i) specific thermal effects of reflective and green roofs [97,98], (ii) urban air quality and particle dispersion through the presence of vegetation [99] (research article), [100] (research article), and (iii) benefits and challenges of growing urban vegetation within the public realm [101].…”

Is there an association between urban greenness and air pollution annoyance?

“…However, research on air pollution annoyance and health is much scarcer in comparison to that on noise annoyance (11). Green spaces are known to reduce air pollution in the urban environment by filtering particulate and gaseous pollutants, deposing them on plant surfaces, increasing their dispersion and altering the local temperature (12,13,14,15). There is, however, another alleged pathway, which has received little attention.…”