Roadside green infrastructure (GI) has attracted worldwide attention for its potentials to alleviate local air pollution. However, previous studies have not clearly characterized the effects of roadside GI on personal exposure levels to vehicular emissions, particularly for cyclists and pedestrians on the pathways between urban roads and vegetative barriers. In this study, field experiments were implemented to measure and compare the concentration levels of particulate matter (PM) and black carbon (BC) on pathways (e.g., bike lanes and sidewalks) and near residential buildings with and without roadside GI. Results show that the presence of GI significantly elevated the particle concentrations over bike lanes and sidewalks. Compared with the GI-free case, an increase of up to 20% and 28% was separately observed for BC and PM on the pathways before GI. This is strongly associated with the impact of GI on local wind fields that impedes the dispersion of traffic-emitted particles on the roadways. However, roadside GI brought a significant reduction of particle concentrations near residential buildings, separately decreasing by about 8% for BC and 6% for PM. Then Computational Fluid Dynamics software was adopted to simulate the diffusion process of traffic-emitted particles in the typical urban scenarios of roadways, pathways, GI, and residential buildings, and further analyze the particle distribution patterns under six roadside GI configurations. Simulation results suggest that tall vegetative barriers can lead to the accumulation of particles on the pathways and increase cyclists' and pedestrians’ exposure to local particulate pollution. The GI case of “tree canopy only” can be a potentially viable choice to reduce particle concentrations on the pathways due to the fact that its better ventilation conditions are more favorable for particle diffusion than other GI configurations. However, compared with the complex GI configurations, the scenario with no roadside GI exhibits more positive effects on decreasing particulate exposure on the pathways. These findings could provide practical insights into roadside GI design and important implications in near-road air quality improvements.

路边的绿色基础设施（GI）因其减轻当地空气污染的潜力而吸引了全世界的关注。但是，先前的研究尚未明确表征路边胃肠道对个人暴露于车辆排放水平的影响，特别是对于骑自行车的人和行人在城市道路与植物屏障之间的路径上。在这项研究中，进行了现场实验，以测量和比较道路（例如自行车道和人行道）以及有或没有路边胃肠道的住宅建筑物附近的颗粒物（PM）和黑碳（BC）的浓度水平。结果表明，胃肠道的存在显着提高了自行车道和人行道上的颗粒浓度。与无地理标志的情况相比，胃肠道之前的路径中，BC和PM分别增加了多达20％和28％。这与地理标志对当地风场的影响密切相关，地理标志影响了交通排放颗粒在道路上的散布。但是，路边的GI显着降低了住宅建筑物附近的颗粒物浓度，BC和PM分别降低了约8％和6％。然后采用计算流体动力学软件，模拟了典型城市道路，小径，地理标志和住宅建筑中交通排放颗粒的扩散过程，并进一步分析了六种路边地理标志配置下的颗粒分布规律。仿真结果表明，高大的植物屏障会导致颗粒在路径上堆积并增加骑车人的 以及行人受到当地微粒污染的影响。由于其更好的通风条件比其他GI配置更有利于颗粒扩散，因此“仅树冠”的GI案例可能是降低路径上颗粒浓度的潜在可行选择。但是，与复杂的GI配置相比，没有路边GI的场景对减少路径上的颗粒物暴露表现出更多的积极影响。这些发现可以提供对路边地理标志设计的实用见解，以及对改善近路空气质量的重要意义。由于其更好的通风条件比其他GI配置更有利于颗粒扩散，因此“仅树冠”的GI案例可能是降低路径上颗粒浓度的潜在可行选择。但是，与复杂的GI配置相比，没有路边GI的场景对减少路径上的颗粒物暴露表现出更多的积极影响。这些发现可以提供对路边地理标志设计的实用见解，以及对改善近路空气质量的重要意义。由于其更好的通风条件比其他GI配置更有利于颗粒扩散，因此“仅树冠”的GI案例可能是降低路径上颗粒浓度的潜在可行选择。但是，与复杂的GI配置相比，没有路边GI的场景对减少路径上的颗粒物暴露表现出更多的积极影响。这些发现可以提供对路边地理标志设计的实用见解，以及对改善近路空气质量的重要意义。