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Project at a Glance

Project Status: complete

Title: Measuring Emissions from the On-Road Vehicle Fleet in West Los Angeles

Principal Investigator / Author(s): Bishop, Gary

Contractor: University of Denver

Contract Number: 17RD015

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels, Transport


A sixteen-year record of on-road emission measurements at a West Los Angeles site (La Brea Ave. and I-10) was continued with an additional data collection campaign in May of 2018. During this campaign, the University of Denver collected 19,259 emission measurements of carbon monoxide (CO), carbon dioxide, hydrocarbons (HC), nitric oxide (NO), ammonia (NH3) and nitrogen dioxide (NO2) from light and medium-duty vehicles. Since 1999 the CO mean emissions have decreased by 84% (70.3 to 11 g/kg), the HC mean emissions by 79% (7.0 to 1.5 g/kg) and the NO mean emissions by 76% (6.6 to 1.6 g/kg). These decreases have happened despite an older fleet (8.9 years) now than prior to the 2008 recession. Over this same time, the 99th percentiles have dropped by more than a factor of three for CO and HC (773 to 212 gCO/kg of fuel and 93 to 31 gHC/kg of fuel) and a factor of 1.6 for NO (53 to 32 gNO/kg of fuel). However, during recent campaigns, the reductions in the 99th percentiles have leveled out for HC and may be slowing for CO, which will likely slow future emissions reductions despite gradual electrification of the fleet.


For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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