Environmental Justice Assessment of Formaldehyde Exposure during a Photochemical Pollution Episode in Southeast Texas

YITING LI, Yusheng Zhao, Michael Kleeman, University of California, Davis

     Abstract Number: 397
     Working Group: Identifying and Addressing Disparate Health and Social Impacts of Exposure to Aerosols and Other Contaminants across Continents, Communities, and Microenvironments

Abstract
Formaldehyde (HCHO) is a ubiquitous organic compound found in urban air across the globe, with concentrations that are typically an order of magnitude higher than concentrations of more complex aldehydes. Many epidemiology studies have demonstrated a correlation between HCHO exposure and cancer risk. HCHO was ranked as the greatest cancer driver of risk across the United States by the US Environmental Protection Agency in the year 2018. Although indoor sources of HCHO can be large, recent studies show that outdoor HCHO concentrations contribute significantly to total HCHO population exposure. HCHO exposure represents a continuing public health risk that must be understood before it can be efficiently mitigated.

Here we calculate primary and secondary HCHO exposures for different race/ethnicity groups living in southeast Texas during a regional summertime air pollution event using a chemical transport model (CTM). Exposure calculations are performed for sixteen different formaldehyde sources using the tagging options available in the CTM. Exposure disparities by race/ethnicity are calculated, and recommendations to reduce these disparities are formulated. The results show that biogenic emissions reacted to form secondary HCHO that accounted for 44% of the total population-weighted exposure across the study domain. Primary refinery and industrial emissions were the largest anthropogenic sources of HCHO exposure in southeast Texas. Mobile sources accounted for 3.5% of the total HCHO population exposure. African American residents were exposed to HCHO concentrations +20% higher than average, mostly due to primary refinery emissions. Asian residents were exposed to HCHO concentrations that were 5% higher than average due to HCHO associated with on-road vehicles, off-road diesel vehicles, and other sources. White residents were exposed to lower-than-average HCHO concentrations because their homes were located further from primary HCHO emissions sources. Disparities in cancer risk that are proportional to HCHO exposure could be reduced by controlling primary HCHO emissions from refineries, or by rezoning larger areas around these facilities for non-residential use.