PM2.5 interactions with vegetation across scales, deposition dynamics, physiological responses and air quality mitigation

Fine particulate matter (PM 2.5 ) is widely recognized for its effects on human health, yet its interactions with vegetation are often examined separately from atmospheric, ecological, and plant science perspectives. PM 2.5 originates from both direct emissions and secondary atmospheric reactions involving SO 2 , NOₓ, NH 3 , and volatile organic compounds. Due to its small size and prolonged atmospheric residence, it can undergo long-range transport and repeatedly interact with vegetation before being removed through dry, wet, or occult deposition. However, deposition does not necessarily represent permanent particulate removal. Instead, vegetation serves as a dynamic interface where PM 2.5 deposition, retention, remobilization, and physiological interactions occur continuously under changing environmental conditions. Plant traits such as leaf surface roughness, epicuticular waxes, trichomes, stomatal characteristics, and canopy architecture strongly regulate particulate capture and persistence, while rainfall, wind, and seasonal canopy changes influence wash-off, resuspension, and redistribution processes. Surface accumulation of PM 2.5 can reduce light interception, disrupt stomatal functioning, and induce oxidative stress, thereby affecting photosynthesis and metabolic activity. Plants respond through structural adjustments and antioxidant defense systems, although these responses vary considerably among species. At broader scales, vegetation can modify local PM 2.5 concentrations through deposition and aerodynamic interactions, but mitigation effectiveness remains highly dependent on vegetation structure, urban morphology, and environmental conditions. This review integrates atmospheric transport, plant functional traits, particulate retention dynamics, physiological responses, and vegetation-mediated mitigation processes to provide a more comprehensive understanding of vegetation as a receptor, regulator, and temporary reservoir of atmospheric particulate matter.