Linking environmental injustices in Detroit, MI to institutional racial segregation through historical federal redlining

Objectives: To identify the most pervasive environmental exposures driving environmental disparities today associated with historical redlining in Detroit. Methods: Detroit's 1939 HOLC shapefile from the Mapping Inequality project was overlaid onto EPA EJScreen and DOT National Transportation Noise maps to analyze differences in current demographic and environmental indicators between historically redlined (D-grade) and non-redlined neighborhoods using simple linear regression and a boosted classification tree algorithm. Results: Historically redlined neighborhoods experienced significantly higher environmental hazards than non-redlined neighborhoods: diesel particulate matter (PM) 12.1% (95% CI: 7.2–17.1%) higher, traffic volumes 32.2% (95% CI: 3.3–69.3%) larger, and hazardous road noise exposure (Leq(24h) >70 dBA) 65.7% (95% CI: 8.6–152.8%) higher. Redlined neighborhoods were near 1.7-times (95% CI: 1.4–2.1) more hazardous waste sites and twice as many (95% CI: 1.5–2.7) Risk Management Plan (RMP) sites. Lifetime cancer risk from inhalation of air toxics was 4.4% (95% CI: 2.9–6.6%) higher, and the respiratory hazard index was 3.9% (95% CI: 2.1–5.6%) higher. Collectively, the most pervasive hazards were proximity to RMP sites, hazardous road noise, diesel PM, and air toxics cancer risk. Conclusions: Historically redlined neighborhoods may face disproportionately higher risks of cancer and adverse respiratory health outcomes from air toxics. Policies targeting air and noise pollution from transportation sources, particularly diesel exhaust, in historically redlined neighborhoods may ameliorate impacts of structural environmental racism from historical redlining in Detroit.

Abas Shkembi, Lauren M. Smith, Richard L. Neitzel