Fried and fatty foods aren’t the only things bad for your arteries — a new study suggests the air you breathe could play a role, too.

Prolonged exposure to air pollution could be linked to heart attacks and strokes by speeding the hardening of the arteries — a condition known as atherosclerosis that is linked with heart disease, according to new research.

The study showed a link between higher concentrations of particulate air pollution and faster thickening of the inner two layers of the carotid artery, as well as a link between slowed progression of atherosclerosis with decreasing air pollution.

The findings are published in the journal PLOS Medicine, and are based on data from 5,362 people ages 45 to 84 who came from six U.S. metro areas that were part of the Multi-Ethnic Study of Atherosclerosis (MESA Air). Over three years, researchers estimated home air pollution levels of all the study participants, as well as their blood vessel health.

On average, the study participants all experienced an average increase in carotid artery thickness of 14 micrometers each year. However, people who lived in more polluted areas experienced faster thickening, compared with those breathing cleaner air.

“Linking these findings with other results from the same population suggests that persons living in a more polluted part of town may have a 2 percent higher risk of stroke as compared to people in a less polluted part of the same metropolitan area,” Sara Adar, an assistant epidemiology professor at the University of Michigan School of Public Health, said in a statement.