Examining Longitudinal Trends in Fine Particulate Matter (Pm2.5) Exposure According to Social Vulnerability in South Carolina

Abstract

Air pollution in the U.S. has declined since the 1970s, but disparities in exposure to harmful air pollutants like fine particulate matter (PM2.5) persist. Previous research has examined associations between air pollution exposure and individual factors such as socioeconomic status or race/ethnicity but seldom explored social vulnerability or temporal trends in South Carolina (a state characterized by significant health issues and inequities). The purpose of this study was to investigate the relationship between PM2.5 and overall social vulnerability in SC from 2000-2018. The CDC/ATSDR Social Vulnerability Index (SVI), which is comprised of four components – minority status and language (comprised of two variables), socioeconomic status (four variables), housing type and transportation (five variables), and household composition and disability (four variables) – was compiled for all census tracts in SC (n=867 as of 2000). Overall SVI was categorized into tertiles (low=289, moderate=290, high=288). North American estimates of annual surface PM2.5 concentration (µg/m3) from Washington University in St. Louis were ascertained for each tract from 2000 through 2018. A repeated measures ANOVA was used to analyze trends and disparities in PM2.5 for low, moderate, and high SVI tracts (controlling for tract rurality). Tracts at the low, moderate, and high vulnerability levels observed respective PM2.5 decreases of 48.1%, 49.1%, and 48.3% from 2000 to 2018. A significant change in mean PM2.5 occurred over the study period (F=24494.3, p<.0001), with a significant tract by SVI tertile interaction (F=3.49, p<.0001). Annual PM2.5 differences relative to the 2000 baseline were significant in six of the 19 years analyzed. High-vulnerability tracts consistently exhibited higher average annual PM2.5 concentrations than their moderate and low-vulnerability counterparts, except in 2012 and 2016. Significant findings were also observed for the SVI components. This study highlights enduring disparities in PM2.5 exposure, particularly among socially vulnerable populations, warranting localized interventions.

Keywords: particulate matter (PM2.5), social vulnerability, Air pollution, disparities, South Carolina