Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA.
Office of Research and Development, U.S. Environmental Protection Agency, Durham, NC, USA; Office of Transportation and Air Quality, U.S. Environmental Protection Agency, Ann Arbor, MI, USA.
Sci Total Environ. 2020 May 15;717:137136. doi: 10.1016/j.scitotenv.2020.137136. Epub 2020 Feb 4.
Communities located in near-road environments face adverse health effects due to elevated exposures to traffic-related air pollution (TRAP). While the use of a combination of solid structures (i.e. sound walls) and vegetation barriers can be an effective TRAP mitigation tool, installing these barriers can also present challenges to local communities. Sound walls are costly, and building these structures often requires the involvement of federal, state, and local permitting agencies. In this paper, we proposed that the use of low-cost, impermeable, solid structures (LISS), e.g., an impermeable thin wooden, plastic or metal fence, combined with vegetation can provide an effective option for local communities to improve near-road air quality due to lower costs and easier implementation. We conducted Large Eddy Simulations (LES) for different design scenarios of LISS and vegetation barriers under various conditions. Our results indicate that (i) combining LISS and vegetation is more effective than either alone, (ii) combining a less dense vegetation and LISS can be as effective as a dense vegetation barrier, (iii) In certain scenarios, depending on wind speed and particle size, vegetation barriers alone might lead to elevated pollutant concentrations; however, combining LISS with vegetation can mitigate those negative impacts, (iv) placing LISS closer to the freeway and in front of the vegetation barrier enhances vertical dispersion of pollutants, and (v) increasing LISS height promotes pollutant concentration reduction. These design recommendations can be used by urban planners, developers, and local community leaders to evaluate and implement green infrastructure to mitigate TRAP.
位于道路附近环境中的社区由于接触到交通相关的空气污染（TRAP）而面临不良健康影响。虽然使用固体结构（即隔音墙）和植被屏障的组合可以是一种有效的 TRAP 缓解工具，但安装这些屏障也会给当地社区带来挑战。隔音墙成本高昂，建造这些结构通常需要联邦、州和地方许可机构的参与。在本文中，我们提出使用低成本、不可渗透的固体结构（LISS），例如不透水的薄木、塑料或金属围栏，结合植被，可以为当地社区提供一种有效的选择，以改善由于成本较低且更容易实施，道路附近的空气质量。我们针对不同设计方案的 LISS 和植被屏障进行了大涡模拟（LES），并在各种条件下进行了模拟。我们的结果表明：（i）LISS 和植被的组合比单独使用任何一种都更有效；（ii）结合不太密集的植被和 LISS 可以与密集的植被屏障一样有效；（iii）在某些情况下，取决于风速和粒子大小，单独使用植被屏障可能会导致污染物浓度升高；但是，将 LISS 与植被结合使用可以减轻这些负面影响；（iv）将 LISS 更靠近高速公路并放置在植被屏障的前面，可以增强污染物的垂直扩散；（v）增加 LISS 的高度可以促进污染物浓度的降低。这些设计建议可被城市规划者、开发商和当地社区领袖用于评估和实施绿色基础设施，以缓解 TRAP。
