Social Inequities in Transportation Noise Exposures in the United States: Urbanicity Modifies that Relationship Between Social Vulnerability and Noise Exposure

Abstract Prior research has explored the unequal distribution of environmental hazards; however, little is known about the relationship between social vulnerability and transportation noise exposure in the U.S., particularly in relation to urbanization levels. We sought to examine the relationship between the Social Vulnerability Index (SVI) and transportation noise exposure across the U.S. at the census-tract level and assessed the moderating effects of urbanization. Multivariate linear regression models were used to assess the relationship between SVI – a composite index consisting of thematic indicators for socioeconomic status (SES), household characteristics, racial/ethnic minority status, and housing/transportation factors – and population-weighted transportation noise exposure at the census-tract level. An interaction term was used in the model to assess the moderating effects of urbanization. Principal component analysis (PCA) and regression (PCR) were employed to extract the features that correlate with specific SVI themes and examine their relationship to transportation noise exposure. Findings from PCA and PCR reveal that in the urban area context, census tracts that score high on all four vulnerability themes of the SVI are positively associated with transportation noise exposure, while an opposite relationship is observed for census tracts that score high in vulnerability with respect to racial/ethnic minority status and household characteristics, but not particularly high in vulnerability for SES or housing/transportation factors, regardless of the urbanization level. Our study underscores the impact of distinct social vulnerability components on transportation noise exposure, revealing variations across different urbanization strata. Highlights Social vulnerability and urbanization levels influence transportation noise exposure. Urban areas show positive associations between SVI and noise; rural areas show inverse trends. PCA and PCR reveal distinct SVI components linked to transportation noise exposure patterns. High SVI urban tracts experience elevated noise; rural racial/ethnic minority tracts are less exposed. Findings inform targeted policies addressing environmental justice and noise mitigation strategies. Competing Interest Statement The authors have declared no competing interest. Funding Statement This work was supported by the University of Washington EDGE Center of the National Institutes of Health [award number P30ES007033]. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability All data produced in the present study are available upon reasonable request to the authors