Air pollution has adverse effects on the health. Now, researchers at NYU Langone Medical Center have linked the levels of fine-particulate-matter pollution to narrowing of the neck arteries, which is stroke-related. People living in highly polluted areas were significantly more likely to show signs of narrowing (stenosis) in their internal carotid arteries, compared to those living in areas with the lowest pollution levels.
The two internal carotid arteries are situated on either side of the neck. They provide most of the brain's blood supply. Stroke often occurs when accumulated plaque breaks off from a narrowed section of an internal carotid artery and blocks smaller vessels in the brain. Researchers analyzed the carotid narrowing data from vascular ultrasound tests for more than 300,000 people living in New York, New Jersey or Connecticut.
Fine particulate matter pollutants, also called 'PM 2.5 pollutants', are particulates with diameters less than 2.5 millionths of a meter. They are most likely to be by-products of combustion engines and burning wood. The pollution data was provided by the Environmental Protection Agency.
Researchers found that subjects in the top fourth polluted areas, ranked by average PM 2.5 levels, were about 24% more likely than those in the bottom quarter to have shown signs of stenosis in either internal carotid artery. Senior investigator Jeffrey S. Berger said, "We spend a lot of time thinking about traditional risk factors for stroke such as high blood pressure, cholesterol, diabetes and smoking. But our data underscore the possibility that everyday air pollution may also pose a significant stroke risk."
Scientists are not yet sure how air pollution contributes to vascular disease. "Our study was a population study, so it can't establish cause and effect, but it certainly suggests the hypothesis that lowering pollution levels would reduce the incidence of carotid artery stenosis and stroke," said Dr. Jonathan D. Newman a cardiologist at NYU Langone Medical Center in the Department of Medicine.
The study was presented at the American College of Cardiology's 64th Annual Scientific Session as a poster presentation and appears online in the Journal of the American College of Cardiology (JACC).