The effects of historical residential redlining on temporal trends of air pollution levels measured near New York City schools

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BACKGROUND AND AIM: In the 1930’s the Home Owners’ Loan Corporation began categorizing neighborhoods based on racial demographics and perceived risk for mortgage investment. This historical practice of redlining has perpetuated racial segregation, poverty and influenced where major sources of air pollution were placed thus placing some schoolchildren at risk of high exposures. While a declining trend of air pollution was reported in New York City (NYC) between 2001 and 2012, little is known about regional differences in air quality improvement. Our objective was to determine recent temporal trends of air pollution from 2009-2018 near NYC schools and examined if trends differed in historically redlined neighborhoods. METHODS: We examined annual average street-level concentrations of BC, PM2.5, and NO2, within a 250-km radius around NYC public schools (2009-2018; N=1828) using NYC Community Air Survey land-use regression models. Neighborhoods were characterized as redlined (N=892) vs. other (N=936). Year of monitoring (interval variable) and historical redlining (binary) were included in linear regression models. To test whether temporal trends of air pollution differ by historical redlining, a multiplicative interaction term was included. Models were further stratified by historical redlining. Annual percent change (APC) in pollutant concentration was calculated. RESULTS:Overall, there was a decreasing trend of BC (APC=-4.9%), PM2.5 (-4.2%), and NO2 (-3.2%). On average, pollutants were higher in redlined vs. other neighborhoods (BC: 1.12±0.29 vs. 0.99±0.27 µg/m3; PM2.5: 9.47±1.47 vs. 8.93±1.42 µg/m3; NO2: 23.5±4.2 vs. 21.4±3.75 ppb; p0.001 for all). A smaller reduction of BC and PM2.5 was observed in redlined neighborhoods, compared to others for BC (APC: -4.7% vs. -5.1%; P-interaction0.001) and PM2.5 (-4.1% vs. -4.3%; P-interaction0.001) but not NO2. CONCLUSIONS:Despite significant reductions in recent annual average BC, PM2.5, and NO2 concentrations across NYC, historically redlined neighborhoods experienced smaller decrease in air pollution compared to others, highlighting a potential ongoing legacy of the discriminatory practice. KEYWORDS: black carbon, nitrogen dioxide, particulate matter, health equity, environmental justice