Highways are a ubiquitous feature of life in the United States, encouraged by a century of investment in automobile infrastructure and associated car-dependent land uses. They pose a major threat to public health. In this review of national scholarship, we document the considerable evidence showing that people living, working, and learning within 300 meters of arterials and interstates are exposed to greater levels of hazardous air and noise pollution than the population overall. This exposure places people who live, work, and attend school close to highways at increased levels of risk for numerous negative health impacts, including lung disease, stroke, and premature birth.

Using Louisville, Kentucky, as a case study, we examine local exposure to highways. Almost 50 percent of residents, a majority of schools, and two-thirds of jobs are located within 300 meters of arterials. Though we find no evidence that people of color are disproportionately exposed to highway pollution, we show that people with incomes below the federal poverty level, households receiving food stamps, renters, and residents of publicly subsidized affordable housing are. Ironically, households without a car are far more likely than those with automobiles to live in neighborhoods with elevated exposure to highway pollution. Recent building permits for apartment buildings indicate that these discrepancies will continue into the future. Government policies are partly to blame: Local decisionmakers have positioned both affordable housing investments and high-density zoning districts near highways, while limiting access to non-car transportation. Through changes in the zoning code, housing policies, and infrastructure investments, Louisville could model new approaches to reducing pollution exposure and advance environmental justice.