Inequitable Exposure to Air Pollution from Vehicles in California

The Union of Concerned Scientists utilized the InMAP (Intervention Model for Air Pollution) to estimate average annual concentrations of PM2.5 in California at a resolution of one square kilometer. By mapping these concentrations to census block groups and integrating data from the 2012–2016 American Community Survey, the study aimed to determine population-weighted exposure by demographic group. The authors justify the use of the reduced-complexity InMAP model over conventional chemical transport models (CTMs) by noting its superior performance on population-weighted metrics and its ability to provide the fine spatial resolution necessary to analyze exposure equity in racially or economically segregated urban areas.

• The study used the InMAP model to estimate average annual concentrations of PM2.5 in California with a maximum resolution of one square kilometer, incorporating tailpipe and refueling emissions from on-road vehicles based on the 2014 US EPA National Emissions Inventory.
• To assess exposure by demographic group, PM2.5 concentrations were mapped to census block groups using area-weighted interpolation and combined with 2012–2016 American Community Survey data, using population-weighted annual average concentration as the primary metric.
• The InMAP model is preferred for equity assessments because its fine spatial resolution allows for meaningful insights into exposure in urban areas with segregated populations, and it performs better on population-weighted metrics than area-based metrics compared to conventional CTMs.
• The analysis assumed a no-effect threshold concentration of zero micrograms per cubic meter for health impacts, as no lower bound has been established for chronic PM2.5 exposure.

APA

Union of Concerned Scientists (2019). Inequitable Exposure to Air Pollution from Vehicles in California. https://www.ucs.org/sites/default/files/attach/2019/02/Inequitable-Exposure-Methods.pdf

Chicago

Union of Concerned Scientists. Inequitable Exposure to Air Pollution from Vehicles in California. 2019. https://www.ucs.org/sites/default/files/attach/2019/02/Inequitable-Exposure-Methods.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=Inequitable Exposure to Air Pollution from Vehicles in California |date=February 2019 |url=https://www.ucs.org/sites/default/files/attach/2019/02/Inequitable-Exposure-Methods.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2019inequitable, author = {{Union of Concerned Scientists}}, title = {{Inequitable Exposure to Air Pollution from Vehicles in California}}, institution = {Union of Concerned Scientists}, year = {2019}, month = feb, url = {https://www.ucs.org/sites/default/files/attach/2019/02/Inequitable-Exposure-Methods.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }