title: Roadside vegetation barrier designs to mitigate near-road air pollution impacts.
abstract: With increasing evidence that exposures to air pollution near large roadways increases risks of a number of adverse human health effects, identifying methods to reduce these exposures has become a public health priority. Roadside vegetation barriers have shown the potential to reduce near-road air pollution concentrations; however, the characteristics of these barriers needed to ensure pollution reductions are not well understood. Designing vegetation barriers to mitigate near-road air pollution requires a mechanistic understanding of how barrier configurations affect the transport of traffic-related air pollutants. We first evaluated the performance of the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model with Large Eddy Simulation (LES) to capture the effects of vegetation barriers on near-road air quality, compared against field data. Next, CTAG with LES was employed to explore the effects of six conceptual roadside vegetation/solid barrier configurations on near-road size-resolved particle concentrations, governed by dispersion and deposition. Two potentially viable design options are revealed: a) a wide vegetation barrier with high Leaf Area Density (LAD), and b) vegetation-solid barrier combinations, i.e., planting trees next to a solid barrier. Both designs reduce downwind particle concentrations significantly. The findings presented in the study will assist urban planning and forestry organizations with evaluating different green infrastructure design options.
authors.affiliation: Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA.
authors.forename: Zheming
authors.initials: Z
authors.lastname: Tong
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA; U.S. Environmental Protection Agency, Office of Transportation and Air Quality, Ann Arbor, MI, USA.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Baldauf
authors.affiliation: U.S. Environmental Protection Agency, Office of Transportation and Air Quality, Ann Arbor, MI, USA.
authors.forename: Vlad
authors.initials: V
authors.lastname: Isakov
authors.affiliation: Jacobs Technologies, 109 TW Alexander Drive, Durham, NC 27713, USA.
authors.forename: Parikshit
authors.initials: P
authors.lastname: Deshmukh
authors.affiliation: Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA. Electronic address: kz33@cornell.edu.
authors.forename: K
authors.initials: K
authors.lastname: Max Zhang
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data; D001673:Biodegradation, Environmental; D004784:Environmental Monitoring; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D001335:Vehicle Emissions
keywords: Air quality; CFD; Dry deposition; Green infrastructure; Particulate matter (PM); Ultrafine particle (UFP); Urban planning