Heart patients could be at an increased risk for peripheral artery disease and hypertension if they live near a busy road, Duke University researchers reported in the American Heart Association journal Arteriosclerosis, Thrombosis and Vascular Biology this week.

While pollution is a known killer—it was responsible for one in every six deaths worldwide in 2015—this was the first large-scale analysis of traffic-related pollution’s effect on coronary and vascular disease, according to an AHA release. Air pollution alone is responsible for millions of deaths due to related cardiovascular disease, stroke, lung cancer and chronic obstructive pulmonary disease.

In the Duke study, researchers evaluated 2,124 individuals living in North Carolina within two miles of a busy road. Cardiac catheterizations were performed to determine each patient’s heart health.

Patients who lived an average of 0.6 miles from a major road saw higher risks for both hypertension and peripheral artery disease, lead author Cavin Ward-Caviness, PhD, and colleagues reported. The link to hypertension was strongest among women and black patients, they said, while the connection to peripheral artery disease was stronger among men and whites.

Forty-six million U.S. adults live with high blood pressure, according to the release, and those people are automatically at an increased risk for developing peripheral artery disease, which can then lead to coronary artery disease or fatal events like heart attacks or stroke.

Previous studies have also tied traffic-related pollution to type 2 diabetes, inflammation and atherosclerosis, the AHA reported.

Ward-Caviness said in the release his study could be an important stepping stone in starting a conversation about zoning in busy cities. Hopefully, he said, various stakeholders, city zoning staff and insurance companies will think of these numbers when deciding where to place schools and nursing homes.

“The more we can start discussions about what the risks are for vascular diseases, the more we can inform the public about ways to reduce those risks,” he said.

According to the release, Ward-Caviness and his team are now planning to analyze the impact of microscopic airborne particles, toxic gases like nitrogen dioxide and ozone and overall neighborhood quality.