title: Quantifying the effect of vegetation on near-road air quality using brief campaigns.
abstract: Many reports of trees' impacts on urban air quality neglect pattern and process at the landscape scale. Here, we describe brief campaigns to quantify the effect of trees on the dispersion of airborne particulates using high time resolution measurements along short transects away from roads. Campaigns near major highways in Queens, NY showed frequent, stochastic spikes in PM2.5. The polydisperse PM2.5 class poorly represented the behavior of discrete classes. A transect across a lawn with trees had fewer spikes in PM2.5 concentration but decreased more gradually than a transect crossing a treeless lawn. This coincided with decreased Turbulence Kinetic Energy downwind of trees, indicating recirculation, longer residence times and decreased dispersion. Simply planting trees can increase local pollution concentrations, which is a special concern if the intent is to protect vulnerable populations. Emphasizing deposition to leaf surfaces obscures the dominant impact of aerodynamics on local concentration.
authors: Department of Mechanical and Aerospace Engineering, Cornell University, Gruman Hall, Ithaca, NY, USA.
authors: Zheming
authors: Z
authors: Tong
authors: Section of Horticulture, School of Integrative Plant Science, Cornell University, Room 23 Plant Science Building, Ithaca, NY 14853, USA. Electronic address: thw2@cornell.edu.
authors: Thomas H
authors: TH
authors: Whitlow
authors: Section of Horticulture, School of Integrative Plant Science, Cornell University, Room 23 Plant Science Building, Ithaca, NY 14853, USA.
authors: Patrick F
authors: PF
authors: MacRae
authors: New York State Agricultural Experiment Station, 630 West North Street, Geneva, NY 14456, USA.
authors: Andrew J
authors: AJ
authors: Landers
authors: Section of Horticulture, School of Integrative Plant Science, Cornell University, Room 23 Plant Science Building, Ithaca, NY 14853, USA.
authors: Yoshiki
authors: Y
authors: Harada
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data; D009519:New York City; D052638:Particulate Matter / Q000009:adverse effects / Q000032:analysis; D014197:Trees / Q000009:adverse effects*; D001335:Vehicle Emissions / Q000032:analysis
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions
keywords: Aerodynamics; Dispersion; Near-road air pollution; PM(2.5); Trees