Ultrafine Particle Concentrations Downwind of Engineered Vegetation Belts along Highway Noise Barriers

ZHIYAO LI, Maryssa Loehr, Daniel Fleischer, Brent Bucknum, Ray Yeager, Aruni Bhatnagar, Jay R. Turner, Washington University in St. Louis

     Abstract Number: 636
     Working Group: Aerosol Exposure

Abstract
Computational fluid dynamics modeling suggests vegetation belts–alone or in tandem with noise barriers–can reduce ultrafine particle (UFP) concentrations downwind of major roadways. Prior measurement studies provide limited evidence for UFP reductions and more studies are needed to establish a firmer scientific basis for the design and implementation of engineered vegetation belts. Green Heart Louisville features an extensive neighborhood greening intervention in a Louisville, KY neighborhood to examine the relationships between urban greenness and cardiovascular health. Vegetation belts were installed adjacent to noise barriers lining a limited access highway bisecting the study area. A series of multi-day field campaigns were conducted to measure ultrafine particle (UFP) concentrations in the study area. For each measurement period, up to three vehicles were equipped with Mixing Condensation Particle Counters (vibration stabilized version of the Brechtel Model 1720 MCPC) and these platforms were used to conduct short-term stationary monitoring on roads just outside the vegetation belt/noise wall and mobile “creeping speed” monitoring on additional nearby streets. We operationally define UFP as the total particle number concentration measured by the MCPC. For crosswind conditions, preliminary results demonstrate ~15% reduction in UFP immediately downwind of a vegetation belt/noise wall combination compared to an adjacent unplanted section (i.e. noise wall only). Data analyses for other wind conditions and measurement strategies are underway and will also be presented.