A new study led by researchers at the University of California found that noise pollution is most prevalent in African-American neighborhoods of America’s most segregated cities. Previous studies have indicated that noise pollution is linked to health problems such as high blood pressure and sleep deprivation.

“Race/Ethnicity, Socioeconomic Status, Residential Segregation, and Spatial Variation in Noise Exposure in the Contiguous United States,” published in the journal Environmental Health Perspectives, had scientists using data from noise-monitoring devices placed across the continental United States by the National Park Service. These devices recorded 1 million hours of sound over a 13-year period ending in 2013. The researchers were able to develop a reliable level of noise pollution for neighborhoods with populations between 600 and 1,300 residents. They then compared this level of noise pollution to demographic population data on the neighborhood level.

“This is yet another study that shows that communities of color bear a disproportionate burden of pollution,” said Rachel Morello-Frosch, a co-author of the study and a professor in the School of Public health at the University of California, Berkeley. “But I think that the innovative piece about this work is that we also show that social inequality, or segregation, makes things worse for everybody.”

The researchers found a strong correlation between noise and race. The study found that neighborhoods with at least 75 percent black residents had median night-time noise levels four decibels higher than in neighborhoods without any black residents. Homeowners can achieve a quiet home by applying soundproofing sheets for walls. Traffic noise was the biggest source of noise pollution.