Urban Noise Pollution Impacts Marginalized Communities and Wildlife Excessively, Study Finds

A loud freight train travels within a few feet of a residential complex and next to train cars filled with coal in Denver, Colorado on Nov. 20, 2015. Kathryn Scott Osler / The Denver Post via Getty Images

Sounds affect our daily lives, from birdsong and soothing melodies to jackhammers and jet engines.

People who live in urban environments are often affected by noise pollution, but, due to systemic injustice, some are impacted more than others. And it not only affects humans, but wildlife as well.

A new study by acoustic ecologists from Colorado State University (CSU) has found that marginalized communities are subjected to more urban noise that is louder, and that this exposure has been associated with negative outcomes for humans and wildlife.

“Understanding how systemic biases influence local ecological communities is essential for developing just and equitable environmental practices that prioritize both human and wildlife well-being. With over 270 million residents inhabiting urban areas in the United States, the socioecological consequences of racially targeted zoning, such as redlining, need to be considered in urban planning,” the authors of the study wrote. “We found strong evidence to indicate that noise is inequitably distributed in redlined urban communities across the United States, and that inequitable noise may drive complex biological responses across diverse urban wildlife, reinforcing the interrelatedness of socioecological outcomes.”

The study, “Inequalities in noise will affect urban wildlife,” was published in the journal Nature Ecology & Evolution.

Sara Bombaci, one of the authors of the study and an assistant professor in the Department of Fish, Wildlife and Conservation Biology at CSU, said that, because people derive benefits from wildlife and nature, ecological degradation compounds the injustices against people living in areas that were formerly redlined, a press release from CSU said. Redlining is now illegal, but it was the practice of discriminatorily denying services or loans to residents of non-white neighborhoods.

“We need to be thinking more about how these systemic injustices and problems are manifesting to shape ecology and evolution,” Bombaci said in the press release.

The researchers looked at the distribution of urban noise in 83 cities in the United States across historical racial divisions. They also examined hundreds of studies on how noise impacts wildlife.

The findings of the study —  the first to evaluate noise inequality in redlined communities — were that louder levels of noise are more commonly found in redlined urban areas, and that they detrimentally affect urban ecosystems in proportion to their volume.

Beginning in 1933, grades were assigned to neighborhoods by the government-sponsored Home Owners’ Loan Corporation based on wealth and race. Neighborhoods deemed “grade A” were richer and whiter, while “grade D” neighborhoods with residents from a variety of ethnic and racial backgrounds had red lines drawn around them. In 1968, redlining was made illegal, but disparities endured in these communities due to decades of divestment.

The research team found that there was a 17 percent higher maximum level of noise in grade D neighborhoods than in grade A neighborhoods. Grades C and D neighborhoods were also more often found to have maximum noise levels higher than the level known to lead to physical pain, hearing loss and stress in humans.

“This is directly linked to structural racism,” Bombaci said. “There’s a clear signal that ties directly to whether these communities were redlined.”

Effects on human health caused by noise pollution include insomnia, stress, hypertension and an increased risk of stroke and heart disease. Persistent loud noise is taxing on wildlife as well. It can affect animal communication, distribution, community structure, foraging, fitness, movement, mating and reproduction. Noise can cause animals to avoid particular areas and can cause some species to be more vulnerable to predators.

Denver is one of many cities that are working toward equitable urban planning in order to improve access to green space and parks in underserved communities. Bombaci pointed out that noise should be a consideration in those plans.

“If we’re adding green space without mitigating impacts of noise, we might not be fully recognizing the benefits of these green spaces,” Bombaci said in the press release.

Bombaci added that continued noise pollution means wildlife may not recover in urban green spaces, but urban planning, noise mitigation and conservation funding can be helpful.

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