Estimating Intra-Urban Inequities in PM2.5-Attributable Health Impacts: A Case Study for Washington, DC

Abstract

Air pollution levels are uneven within cities, contributing to persistent health disparities between neighborhoods and population sub-groups. Highly spatially resolved information on pollution levels and disease rates is necessary to characterize inequities in air pollution exposure and related health risks. We leverage recent advances in deriving surface pollution levels from satellite remote sensing and granular data in disease rates for one city, Washington, DC, to assess intra-urban heterogeneity in fine particulate matter (PM_2.5)- attributable mortality and morbidity. We estimate PM_2.5-attributable cases of all-cause mortality, chronic obstructive pulmonary disease, ischemic heart disease, lung cancer, stroke, and asthma emergency department (ED) visits using epidemiologically derived health impact functions. Data inputs include satellite-derived annual mean surface PM_2.5 concentrations; age-resolved population estimates; and statistical neighborhood-, zip code- and ward-scale disease counts. We find that PM_2.5 concentrations and associated health burdens have decreased in DC between 2000 and 2018, from approximately 240 to 120 cause-specific deaths and from 40 to 30 asthma ED visits per year (between 2014 and 2018). However, remaining PM_2.5-attributable health risks are unevenly and inequitably distributed across the District. Higher PM_2.5-attributable disease burdens were found in neighborhoods with larger proportions of people of color, lower household income, and lower educational attainment. Our study adds to the growing body of literature documenting the inequity in air pollution exposure levels and pollution health risks between population sub-groups, and highlights the need for both high-resolution disease rates and concentration estimates for understanding intra-urban disparities in air pollution-related health risks.

Keywords: PM2.5‐attributable health impacts; environmental justice; fine particulate matter; health inequities; intra‐urban baseline disease rates; intra‐urban health risks.

Figure 1

Temporal trends in annual baseline disease rates from District of Columbia Department of Health and annual mean PM_2.5 concentrations (μg/m³, black dotted line) between 2000 and 2018 (top panel) and annual PM_2.5‐attributable excess cases for premature mortality between 2000 and 2015 and asthma ED visits between 2014 and 2018 (bottom panel). In the bottom panel, solid line represents the application of annual baseline disease rates (BDR) and PM_2.5, and dashed lines represent the application of annual BDR with 2018 PM_2.5 concentrations. Health endpoints: ALL, All‐cause mortality; AST, Asthma ED visits; COPD, Chronic Obstructive Pulmonary Disease; IHD, Ischemic Heart Disease; LC, Lung Cancer; STR, Stroke.

Figure 2

PM_2.5‐attributable excess mortality and asthma ED visit rates at the neighborhood scale (2011–2015 average). Baseline disease rates underlying these estimates from the DC DOH are at the neighborhood‐level for all‐cause mortality (ALL) and ischemic heart disease (IHD); zip code‐level for asthma ED visits (AST); and ward‐level for chronic obstructive pulmonary disease (COPD), lung cancer (LC), and stroke (STR).

Figure 3

PM_2.5‐attributable health impacts (2011–2015 average) at the neighborhood scale. Top: The distribution of PM_2.5‐attributable mortality rates (per 100,000 people for all mortality outcomes and per 10,000 people for asthma ED visits) for each health endpoint and each of the 47 DC neighborhoods with available health data. Bottom: The distribution of sociodemographic variables across DC neighborhoods (see Section 2 for variable definitions). The color gradient used in all panels represents that of the PM_2.5‐attributable all‐cause mortality rates (inset legend). Data points are randomly scattered across the x‐axis for plotting purposes.

Figure 4

PM_2.5‐attributable mortality rates (per 100,000 people) for all‐cause mortality and percent (%) Black distribution by neighborhood across Washington, DC. Data represent equal intervals and 2011–2015 means.

Figure 5

Neighborhood‐level PM_2.5‐attributable rates for asthma ED visits (Asthma) per 10,000 people and PM_2.5‐attributable mortality rates for COPD, lung cancer (LC) and stroke per 100,000 people using (a) DOH disease rates and (b) the integrated CDC‐DOH disease rates, and (c) percent difference between (a and b) [(CDC‐DOH ‐ DOH)/DOH]. Results are aggregated to neighborhood scale for all health outcomes, though DOH disease rate inputs for panel (a) are at zip code level for asthma ED visits and ward level for COPD, lung cancer, and stroke.