Abstract: Street canyon greening is an important part of urban green infrastructures, playing a critical role in controlling air pollution. Plant type, configuration and structural characteristics could significantly affect the absorption, deposition, and diffusion of particulate matters (PMs) in the street canyon, with consequence on pedestrian health. Optimizing the design of street canyon greening is a research hotspot in multiple disciplines. Here, we summarized the greening parameters, discussed the research methods and regulation mechanism of PMs diffusion by greening in street canyon, and further analyzed the attenuation efficiency of greening to PMs and related affecting factors (street morphology, street direction, building roof form, sky view factor, meteorological factors and emission intensity). Finally, we proposed that further research should focus on the parameterization, multifactor coupling, multi-scale fusion, and the tradeoffs between multiple ecological functions of street canyon greening, which could provide theoretical basis for air quality improvement and greening construction in street canyons.

Key words: greening parameter, particulate matter, diffusion mechanism, affecting factor.