ARB Research Seminar

This page updated November 18, 2019

A Method to Prioritize Sources for Reducing High PM2.5 Exposures in Environmental Justice Communities in California

Photo of Joshua Apte, Ph.D.

Joshua Apte, Ph.D, The University of Texas at Austin

November 26, 2019 at 9:30 a.m.
Sierra Hearing Room, Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


This project developed and applied a new method for evaluating inequality in exposure to fine particulate matter (PM2.5). The method utilizes a spatial database built from a simplified chemical transport model and census data for groups of different ages, income levels, and race/ethnicity. Given information on location and emission rates of PM2.5 or precursor emissions (NOX, SO2, NH3, or VOCs), one can calculate, for a specific source, the amount of PM2.5 inhaled by the total population and exposure differences among demographic groups. Applying this model to an inventory of anthropogenic emissions sources in California shows differences in per-capita exposure of up to 15% by income and 35% by race. The two top sources of exposure, on-road vehicles and industrial activity, contribute most to the exposure disparity by race, in absolute terms. Some minor sources result in higher than average exposure differences among demographic groups, although they do not contribute much to the total exposure concentrations. For example, petroleum refining and aircraft emissions result in over 70% and 120% higher exposures for black populations than the average population, respectively. Patterns in exposure disparity vary among population groups, with some source categories most severely affecting one particular group. This impact-oriented evaluation of emission sources can help decision makers to screen emission-reduction targets for further investigation with more sophisticated methods and achieve environmental justice goals.

Speaker Biography

Joshua Apte is an assistant professor of environmental engineering at the University of Texas at Austin. His work focuses on human exposure to air pollution in the built environment. His research interests include methods for air pollution assessment at local and global scales; atmospheric aerosol dynamics; and air quality, environmental justice, and environmental sustainability in low-income areas. A Berkeley native who has worked extensively in India, Dr. Apte has worked in partnership with the Environmental Defense Fund and Google to complete an extensive mobile monitoring campaign throughout the San Francisco Bay Area. Apte was the inaugural ITRI-Rosenfeld Postdoctoral Fellow at Lawrence Berkeley National Laboratory and a Fulbright-Nehru Fellow at the Indian Institute of Technology, Delhi. He holds a Ph.D. in Energy and Resources from UC Berkeley.

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