California Air Resources Board

Principal Investigator/Author: Sandeep Kishan

Contractor: Eastern Research Group

Sub-contractors: Opus Inspection & University of Denver

Contract Number: 20RD001

Project Status: Completed June 2024

Relevant CARB Programs: Community Air Protection, Community Air Protection Incentives, Mobile Source Emissions Inventory, Advanced Clean Cars, Zero Emission Vehicle, Enhanced Fleet Modernization, Clean Vehicle Rebate Project

Topic Areas: Environmental Justice, Air Pollution Exposure,  Light-Duty Vehicle Research, Heavy-Duty Vehicles, Heavy-Duty Vehicle Research, Advanced Technology & Low Carbon Transit, Zero-Emission Vehicles

Research Summary:

Between 1999 and 2018, the California Air Resources Board (CARB), the California Inspection and Maintenance Review Committee and the Coordinating Research Council have sponsored studies to measure light-duty vehicles (LDV) exhaust emissions using a remote sensing device (RSD) at a West Los Angeles roadside location (ramp from South La Brea Avenue southbound to Interstate-10 eastbound). The longitudinal data shows that the LDV fleet has generally become cleaner over the years. Despite this progress, however, LDVs continue to be a major source of oxides of nitrogen (NOX) and reactive organic gases (ROG) emissions in the region, contributing around 20 percent of NOX emissions and 25 percent of ROG emissions from all anthropogenic sources in Los Angeles County in 2015. The longitudinal data also suggests significant emission disparities between vehicles registered in socioeconomically disadvantaged communities and those registered in non-disadvantaged communities in the Los Angeles area.

In order to effectively reduce air quality disparities across communities for enhanced environmental justice, CARB needs a substantial set of vehicle emissions data throughout California, especially those reflecting real-world driving conditions such as RSD measurements. This project uses roadside-deployed remote sensing devices (RSD) to measure exhaust carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOX) emission rates from light-duty vehicles (LDV) and heavy-duty vehicles (HDV) with downdraft exhaust tailpipes at eight (8) California locations. The project uses the collected data to evaluate vehicle emission disparities between socioeconomically disadvantaged and non-disadvantaged communities across the State, to continue tracking long-term fleet emission trends, to evaluate United States (U.S.)-Mexico border-crossing vehicles’ air pollution impact on border communities, to gauge electric vehicle penetration in disadvantaged communities, and to evaluate Smog Check program attributes including fraud quantification, change-of-ownership program areas, un-registered/out-of-state vehicles, biennial testing cycle (time since the last inspection), and model year exemptions.

Keywords: communities, environmental justice, reducing disparities, oxides of nitrogen (NOx) emissions, NOx reductions, criteria pollutants, priority communities, CalEnviroScreen (CES), clean technology, incentives, light-duty vehicle, heavy-duty vehicle, zero-emission vehicle (ZEV), advanced technology, air quality, volatile organic compounds (VOCs), disadvantaged communities