Light pollution inequities in the continental United States: A distributive environmental justice analysis

Excessive exposure to ambient light at night is a well-documented hazard to human health, yet analysts have not examined it from an environmental justice (EJ) perspective. We conducted the first EJ study of exposure to light pollution by testing for socially disparate patterns across the continental United States (US). We first calculated population-weighted mean exposures to examine whether ambient light pollution in the US differed between racial/ethnic groups. We then used multivariable generalized estimating equations (GEEs) that adjust for geographic clustering to examine whether light pollution was distributed inequitably based on racial/ethnic composition and socioeconomic status across US neighborhoods (census tracts). Finally, we conducted a stratified analysis of metropolitan core, suburban, and small city-rural tracts to determine whether patterns of inequity varied based on urban-rural context. We found evidence of disparities in exposures to light pollution based on racial/ethnic minority and low-to-mid socioeconomic statuses. Americans of Asian, Hispanic or Black race/ethnicity had population-weighted mean exposures to light pollution in their neighborhoods that were approximately two times that of White Americans. GEEs indicated that neighborhoods composed of higher proportions of Blacks, Hispanics, Asians, or renter-occupants experienced greater exposures to ambient light at night. Stratified analyses indicated that those patterns of inequity did not substantially vary based on urban-rural context. Findings have implications for understanding environmental influences on health disparities, raise concerns about the potential for a multiple environmental jeopardy situation, and highlight the need for policy actions to address light pollution.