Naomi Zimmerman

Traditionally, vehicle emissions measurements have relied on reference-grade instruments whose high cost and complexity have limited their deployment in real-world environments. New simple-to-operate, low-cost sensing technologies are a potential solution to this problem. This work aims to validate whether low-cost sensors, with proper calibration, could measure vehicle emissions and could support analysis of emission trends. Under that umbrella, this work provides a comprehensive low-cost solution to the measurement of vehicle emissions factors within the vehicle fleet. The Sensit Real-time, Affordable, Multi-Pollutant (RAMP) monitors measuring PM₂.₅, NO, NO₂, CO₂, O₃, and CO were the low-cost sensor used. The RAMPs were first calibrated based on a collocation with a near-road regulatory site. To assess their suitability of measuring vehicle emissions, six RAMPs were deployed in three parking garages on the UBC Vancouver campus from April–August 2019. UBC Parking Services provided real-time vehicle counts to help validate our method. After sensor calibration, integrated pollutant and CO₂ signals were converted to fuel-based emission factors (EFs) by developing a background subtraction and plume identification algorithm. The calculated EFs fell within the range of previous studies. Evening-vehicle leaving EFs when vehicles were cold were 10-50% higher than in the morning. We also observed a disproportional contribution of high emitters; the top 25% of plumes contributed 45-65% of total emissions. The findings indicate that low-cost sensors are a promising technology for real-world vehicle emissions measurement.

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