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Determining Fleet-based Vehicle Emission Factors Using Low-cost Sensor Packages: A Case Study across Three Parking Garages
Bingqi Liu, NAOMI ZIMMERMAN, University of British Columbia
Abstract Number: 544
Working Group: Combustion
Abstract
Traditionally, measurements of vehicle emissions have relied on reference-grade instruments whose complex operation and high cost have limited their deployment in real-world environments. With new low-cost sensing technologies, continuous measurements of vehicle emissions are now possible in traffic-impacted real-world environments, such as parking garages, where exhaust from on-board engines at low-speed, idle, and cold-start operation can severely affect the air quality.
In this study, the Sensit Real-time, Affordable, Multi-Pollutant (RAMP) monitor for measuring PM2.5, NO, NO2, CO2, O3 and CO was deployed in six locations across three parking garages on the UBC Vancouver campus from April – August 2019. One sensor was located at the entrance to the parking garage, and the other in the main vehicle corridor furthest from the parking garage exterior where ventilation is poorest. The RAMP sensors measured the air quality every 10 seconds, providing a high time-resolution dataset of the real-world concentration of traffic-related air pollutants. In addition to the air pollution data, UBC Parking Services provided vehicle count and timing information to better associate pollutant spikes with vehicle patterns.
The integrated pollutant and CO2 signals were converted to fuel-based emission factors for the five pollutants measured by the RAMP monitors and to measure the relative impact of cold-start. We report PM2.5, CO, and NOx emission factors in-line with previously calculated emission factors using regulatory grade instruments. We also found that emission factors from vehicles leaving the garages in the evening (simulated cold start) were up to 50% higher than emission factors from vehicles entering the garages in the morning.