Air pollution found to have greater impact on mental health in historically redlined New York neighborhoods

Air pollution is bad for mental health. That much is clear. Now new research shows that the impact can be even worse in neighborhoods that have historically been redlined.

Researchers from the University at Buffalo looked at 17 cities in New York State where longstanding federal housing policies once prohibited neighborhoods of color from getting mortgages. Although the practice was banned in 1968, researchers found that elevated levels of air pollutants in these neighborhoods in the state were disproportionately linked to more emergency room (ED) visits for mental health disorders.

“There was a significant association between air pollutant exposure and emergency room visits across neighborhoods in these cities, but this was most pronounced in neighborhoods where the rules were not being followed, negatively impacting the vulnerable populations who still live there,” said Eun-Hye Enki Yoo, Ph.D., associate professor of geography in the UB College of Arts and Sciences.

Yoo is the lead author of the studywhich appeared in the October 20 issue of Science of the total environment.

Linking pollution to ER visits

Redlining emerged from the government-insured mortgages of the New Deal era. The Federal Housing Administration (FHA) rated communities’ loan risk from “A” to “D,” with D considered the riskiest and colored red on color-coded maps. These D-rated—or redlined—neighborhoods, not coincidentally, had higher populations of nonwhite residents, as the FHA concluded that homes near black residents could lose property values.

Research has shown that D-rated neighbourhoods still suffer from poorer air quality due to proximity to industry and motorways, as well as poorer mental health, among other poor health outcomes.

“The next logical question was whether these mental health outcomes are, at least in part, due to harmful environmental exposures,” said study co-author John Roberts, Ph.D., associate professor of psychology and associate director of the division of clinical training in the UB department of psychology.

Elevated pollutant levels are considered risk factors for anxiety, depression, schizophrenia, substance use disorders and dementia, but to substantiate a direct link, Yoo and Roberts collected anonymized patient records from the New York State Department of Health from 2005-16 and compared the data to daily air quality predictions from machine learning models. They focused on 17 cities where the federal government drew redlining maps, including Buffalo, Niagara Falls, Rochester, Albany and the boroughs of New York City.

They found that when levels of two pollutants, particulate matter and nitrogen dioxide, were elevated in neighborhoods rated D, emergency room visits for mental health disorders increased by 1.04% and 0.44%, respectively, two days later.

In neighborhoods rated A, which the FHA once considered the least risky, no association was found between increased pollution levels and subsequent higher emergency room visits.

However, the researchers note that the sample size for the A-rated neighborhoods was low, so they also compared the combined data from A- and B-rated neighborhoods with the combined data from C- and D-rated neighborhoods. While particulate matter had a significant effect on ER visits in both neighborhood groups, nitrogen dioxide, a gas associated with fossil fuel combustion, had no such effect in the A and B groups.

“Of course, there are many reasons, including social determinants of health, why there are more ER visits in one area than another, but we have methods, like case-crossover design, that allow us to control for pre-existing conditions and socioeconomic status,” Yoo said. “So the data showed pretty convincingly that redlined neighborhoods bear the burden of air pollution-related mental health problems.”

The study also found that the link between elevated pollutant concentrations and more emergency room visits only occurred at average temperatures, 40 to 70 degrees Fahrenheit, and that children under 18 and adults ages 35 to 64 were more sensitive to the impact of air pollutants on their mental health.

“Both findings suggest that being outdoors is an important factor in pollutant exposure, as people spend most time outdoors on days with mild weather and younger people generally spend more time outdoors than older people,” Yoo said.

Studies from Buffalo and beyond coming soon

Yoo will install 30 air monitors in Buffalo’s East Side, a predominantly Black community with disproportionately negative health outcomes. The goal is to provide even more accurate and localized air quality data than that provided by the predictive models in the current study.

Yoo is also collaborating with Oregon Health and Science University to analyze air pollution and mental health in historically redlined neighborhoods across the country.

“New York is not necessarily representative of the entire United States, so we’re excited to expand the framework of this study to a national analysis,” Yoo said. “We hope that more direct evidence can lead to policy changes to address this problem.”