Measuring the Impacts of Bus Electrification Using a Low-Cost Sensor Network in Chicago, IL

JONATHAN LIU, Scott Counts, Madeleine Daepp, University of California, Los Angeles

     Abstract Number: 524
     Working Group: Urban Aerosols

Abstract
In this project, we use a network of low-cost air sensors to compare the local air quality impacts of bus fleet electrification. In recent years, major metropolitan areas have been steadily reducing the environmental impacts of bus fleets, a major source of noise and air pollution, by introducing alternative fuel types and engine systems, the latter including hybrid-electric ICE buses and all-electric buses. While hybrid-electric buses and all-electric reduce and eliminate tailpipe emissions, respectively, less is known about how electrification affects non-exhaust particulate matter (PM) emissions, including brake and tire wear. Project Eclipse is a hyperlocal environmental sensing platform which includes custom designed internet-connected low-cost air quality sensors armed with PM2.5, NO2, CO, SO2, and O3 sensors. This project uses (1) real-time air quality data from a network of over 100 air sensors primarily installed at urban bus stops combined and (2) public transit data from the Chicago Department of Transportation to better understand the local air quality impacts of buses. In this study, we compare how local concentrations of NO2, a tailpipe tracer, and PM2.5, emitted through both exhaust and non-exhaust emissions, change during bus arrival and departure. Using bus fleet data, we compare how the ratio of NO2 to PM2.5 differs between bus type across the city of Chicago.