Scientists and medical doctors have long known about the connection between air pollution and illness. Now, a new study links toxic air to Alzheimer’s disease, which is the sixth leading cause of death in the United States.

The study was published last week (November 20) in the neurology journal Brain. Researchers followed 998 women between the ages 73 and 87 who did not have dementia. Over 11 years, scientists gave these women periodic learning and memory tests. Reports The New York Times:

[Scientists also] used magnetic resonance imaging to detect brain atrophy, or wasting, and then scored the deterioration on its degree of similarity to the brain atrophy characteristic of Alzheimer’s disease. They matched Environmental Protection Agency data on air pollution to the women’s residential addresses.

Findings supported that lower test scores correlated with greater exposure to PM 2.5, particulate matter that easily penetrates into the lungs and bloodstream and is one of the deadliest environmental toxins.

PM 2.5 alters brain structure, which then accelerates memory decline,” lead author, Diana Younan, a postdoctoral research associate at University of California Environmental Health Centers, told The Times. “I just want people to be aware that air pollution can affect their health, and possibly their brains.”

As Colorlines has previously reported, air pollution has gone up across the United States since President Donald Trump took office. This is largely a result of a rise in ozone, nitrous oxide and particulate matter, which are three types of air pollutants. Aside from the overall dangers present when the air is toxic, the threats are exaggerated for communities of color in the United States. A November 2017 joint study from the National Association for the Advancement of Colored PeopleClean Air Task Force and National Medical Association found that the air Black Americans breathe is nearly 40 percent more polluted than that of their White counterparts.

According to a 2016 report from Alzheimer’s Assocation, some people of color are also at a higher risk for acquiring the disease. The organization found that African Americans are two times more likely than White Americans to have Alzheimer’s and other dementias; for Latinx people, the chances are one and one-half times more than Whites.

In an article on the study, Andrew Petkus, assistant professor of clinical neurology at USC’s Keck School of Medicine, said, “Our hope is that, by better understanding the underlying brain changes caused by air pollution, researchers will be able to develop interventions to help people with or at risk for cognitive decline.”