Pollution and Brain Health

Recent studies have provided evidence that improvements in cognitive decline are linked to a drop in exposure to high levels of air pollution.

The researchers evaluated effects of a fine particulate, known as PM2.5, on brain health. The particulate is produced by cars and factories and, once inhaled, passes directly through the blood-brain barrier that normally protects the brain. Long-term exposure to these same particulates has been linked to premature death, especially in those with chronic heart and lung disease.

Two University of Southern California Leonard Davis School of Gerontology researchers reported their independent research in a letter published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

In a follow-up to a 2004 study, the first researcher found that older adults with fewer than eight years of education did not have the same risk of cognitive impairment from exposure to PM2.5s. The likely reason for the reduced risk was a 25% decrease in PM2.5 air pollution in the participants’ neighborhoods since 2004. In fact, few of the participants lived in places that exceed the Environmental Protection Agency (EPA) air quality standards.

The second researcher also found improvements in neurotoxicity—the damage to the brain or nervous system caused by exposure to a toxic substance—of PM2.5 air pollution in mice over more than a decade of research.

The results of these studies emphasize the importance on brain health of the gains made to improve air quality. From 2000 to 2020, the PM2.5 level in the US declined by 41%, according to the EPA.