Green infrastructure for air quality improvement in street canyons

Street canyons are generally highly polluted urban environments due to high traffic emissions and impeded dispersion. Green infrastructure (GI) is one potential passive control system for air pollution in street canyons, yet optimum GI design currently unclear. This review consolidates findings from previous research on assesses the suitability of different forms terms local quality improvement. Studies effects various options (trees, hedges, green walls, screens roofs) critically evaluated, synthesised, possible recommendations summarised. In addition, measurement methods used quantifying effectiveness greening reduction analysed. Finally, we explore studies that have compared plant species mitigation. We conclude influences depend canyon geometry, meteorological conditions vegetation characteristics. roofs potentially viable existing where there typically a lack available planting space. Particle deposition leaves usually quantified by leaf washing experiments or microscopy imaging techniques, latter which indicates size distribution more accurate. The pollutant capacity largely depends its macromorphology relation physical environment. Certain micromorphological traits also positively correlate with deposition, including grooves, ridges, trichomes, stomatal density epicuticular wax amount. complexity limited number novel mean offering specific unfeasible. highlights need further research, particularly walls screens, substantiate their efficacy investigate technical considerations.