LAUSR

RATIONALE Environmental threats and poorly controlled asthma disproportionately burden Black people. Some have attributed this to socioeconomic or biologic factors; however, racism, specifically historical redlining, a US discriminatory mortgage lending practice in existence between the 1930s-1970s, may have actuated and then perpetuated poor asthma-related outcomes. OBJECTIVES To link historical redlining (institutional racism) to contemporary environmental quality- and lung health-related racial inequity. METHODS Leveraging a broadly-recruited asthma registry, we geocoded 1,034 registry participants from Pittsburgh/Allegheny County, Pennsylvania, USA to neighborhoods subjected to historical redlining, as defined by a 1930s Home Owner's Loan Corporation (HOLC) map. Individual-level clinical/physiologic data, residential air pollution, demographics, and socioeconomic factors provided detailed characterization. We determined the prevalence of uncontrolled and/or severe asthma and other asthma-related outcomes by HOLC (neighborhood) grade ("A"-"D"). We performed a stratified analysis by self-identified race to assess the distribution of environmental and asthma risk within each HOLC grade. MEASUREMENTS AND MAIN RESULTS The registry sampling overall reflected Allegheny County neighborhood populations. The emissions of carbon monoxide, filterable particulate matter <2.5 microns (PM2.5), sulfur dioxide (SO2), and volatile organic compounds (VOCs) increased across HOLC grades (all p≤0.004), with "D" neighborhoods encumbered by the highest levels. The persistent, dispersive socioenvironmental burden peripherally extending from "D" neighborhoods, including racialized access to healthy environments (structural racism), supported a long-term impact of historical/HOLC redlining. The worst asthma-related outcomes, including uncontrolled and/or severe asthma (p<0.001, Z=3.81), and evidence for delivery of sub-optimal asthma care occurred among registry participants from "D" neighborhoods. Furthermore, elevated exposure to filterable PM2.5, SO2, and VOCs emissions (all p<0.050) and risk of uncontrolled and/or severe asthma (relative risk [95% confidence interval] = 2.30 [1.19, 4.43], p=0.009) demonstrated inequitable distributions within "D" neighborhood boundaries, disproportionately burdening Black registry participants. CONCLUSIONS The racist practice of historical/HOLC redlining profoundly contributes to long-term environmental and asthma-related inequities in Black adults. Acknowledging the role racism has in these outcomes should empower more specific and novel interventions targeted at reversing these structural issues.