Abstract:
In order to assess the characteristics of air pollutants in proximity to major roadways, a mobile monitoring campaign took place using the University of Washington Center for Clean Air Research (CCAR) mobile instrument platform designed to measure concentrations of particles and gases while continuously on the move. The CCAR platform followed a predetermined route in Albuquerque, New Mexico, over seven sequential days in April, 2012 during the evening commute timeframe. A series of roads, parallel to each other and Interstate 40, and beginning approximately 30 meters from the interstate, were traversed at least two times per observation day in an effort to tease-out changes in the chemical and physical properties of traffic-related pollutants as they age with distance from roadway. Metrics obtained during the monitoring campaign include: light scattering coefficients, light absorption coefficients, particle-bound polycyclic aromatic hydrocarbons (PAHs), particle optical diameters, particle number concentrations, ozone (O<sub>3</sub>), nitric oxide (NO), oxides of nitrogen (NO<sub>x</sub>), carbon monoxide (CO), carbon dioxide (CO<sub>2</sub>), integrated volatile organic compounds (VOCs) and location. Spatially resolved measurements were obtained for several of these reactive species as well as non-reactive tracers of vehicle exhaust. Two distinctive dispersion patterns were captured: 1) a symmetric pattern on either side of the interstate associated with low wind speeds; and 2) an asymmetric pattern with a dominant downwind influence. An expected decline with distance from roadway for several traffic-related pollutants, indicative of the dispersion process, was observed for the downwind near-roadway region. Additionally, an expected decrease in O<sub>3</sub> nearing the interstate was observed due to its consumption by NO from roadway emissions. The innovative use of mobile monitoring allows for improved estimates of near-roadway gradients in air pollution, when compared with traditional stationary site sampling. Spatially resolved measurements allow for additional insight into the physical and chemical aging phenomena of traffic-related pollutants in the vicinity of major roadways.
URI
http://hdl.handle.net/1773/23407
