Racial and ethnic inequities to noise pollution from transportation- and work-related sources in the United States.

Background: Racial and ethnic inequities in environmental noise exist in the US, partially attributable to historical structural racism. However, previous studies have not considered the totality of people's exposures. Since people spend most of their waking time at work, there is a need to consider cumulative exposure to noise both in and out of the workplace to understand who is most at risk of noise pollution-related adverse health outcomes.

Objectives: To (1) investigate whether racial and ethnic minority communities are disproportionately burdened by transportation- and workplace-related noise pollution, and (2) assess whether structural racism through historically redlined neighborhoods with sustained mortgage discrimination partially contribute to the hypothesized inequity.

Methods: We characterized the prevalence of workplace noise and transportation noise exposure by census tract across the US. We analyzed the census tract-level association between racial and ethnic composition and the population exposed to both transportation- and workplace-related noise pollution in the 2010s using geospatial models. We then assessed census tract-level associations with transportation and workplace noise pollution using historical redlining in the 1930s as the primary covariate, stratified by mortgage discrimination in the 1990s using a similar geospatial model, controlling for census tract-level indicators of low socioeconomic status.

Results: Higher percentages of racial and ethnic minority individuals, particularly Hispanic/Latino and non-Hispanic Black Americans, were associated with significantly higher odds of exposure to both transportation and workplace noise (odds ratio = 8.59, 95% CI: 7.38-10.0, when comparing within-metropolitan area, highest to lowest quintile percentages). These disparities are particularly profound in urban areas. Urban tracts which experienced residential segregation in the 1930s, even without sustained mortgage discrimination in the 1990s, have a significantly higher percentage of individuals exposed to both transportation and workplace noise today compared to those without historical segregation (1.55%, 95% CI: 1.37-1.74). This inequity is even higher among historically segregated tracts that experienced sustained mortgage discrimination (1.83%, 95% CI: 1.66-2.01).

Significance: These findings can advance environmental justice initiatives by informing regulatory action to protect communities of color from noise pollution both environmentally and during work.

Impact: Our study provides evidence that neighborhoods with a higher proportion of racial and ethnic minority individuals are cumulatively burdened by noise pollution both during work and from transportation sources in their home communities. This suggests that not incorporating workplace exposures when assessing environmental impacts may overlook the most burdened communities. Future environmental justice efforts and policies should consider assessing workplace exposures to reduce environmental health disparities more effectively.