AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Mapping Urban Air Quality in Oakland, CA with Google Street View Vehicles
JOSHUA APTE, Kyle Messier, Shahzad Gani, Melissa M. Lunden, Roel Vermeulen, Christopher Portier, Steven Hamburg, University of Texas at Austin
Abstract Number: 625 Working Group: Urban Aerosols
Abstract Urban concentrations of traffic air pollutants vary sharply over fine spatial scales. However, spatial variation in population exposure to these pollutants is not usually well represented by routine fixed-site observations. Data from mobile air quality monitoring platforms can contribute to a richer understanding of intraurban variation in air pollution.
This study analyzes a dataset of routine mobile air quality measurements in Oakland, CA collected by a fleet of Google Street View cars equipped with fast-response (1 Hz) particle and gas instrumentation. These vehicles collect 40-60 h per week of on-road daytime air quality measurements, including black carbon (BC), size-resolved particulate matter (PM), ultrafine particles (UFP) and nitrogen oxides (NO and NO$_2). The dataset presented here incorporates >1200 h and >30,000 km of on-road data collected from May 2015 – April 2016. Within our core sampling region, we made ≥ 20-40 sampling trips along every public street, yielding ~20,000 repeatedly sampled 30 m road segments. We employ a suite of data reduction routines to yield stable estimates of time-averaged spatial patterns in daytime air quality.
The high-resolution maps that emerge from our data reduction exhibit consistent spatial patterns. For pollutants with a strong primary source (BC, NO, UFP), concentrations on highways are approximately twice as high on highways as on arterial streets, which in turn have levels approximately twice as high as residential streets. Pollutant concentrations decay away from freeways in a manner that can be well represented by a simple two-component exponential model. The degree of decay away from highways varies by pollutant, and is least sharp for pollutants for with a major secondary contribution, such as NO$_2. Consistent concentration hotspots are notable for the primary pollutants at major intersections, on roads with heavy-duty diesel traffic, and on stretches of highway prone to traffic congestion.