Sept. 15 (UPI) -- Exposure to high levels of air pollution can increase the risk for stroke in people with atrial fibrillation by more than 20%, a study published Tuesday by JAMA Network Open found.
For every 6% increase in levels of air pollution exposure, the risk for stroke in adults with the heart condition, known as AFib, increased by 8%, said researchers at the University of Pittsburgh.
The findings are based on an analysis of more than 31,000 adults with AFib living in western Pennsylvania, a region "with historically high industrial pollution," according to the researchers.
"We found that pollution exposure increases stroke risk in people with Afib in a large cohort of people who live in Allegheny County, Pa., [which] is an important place to study pollution because of the history of extensive industrial exposures in the area," study co-author Dr. Jared Magnani told UPI.
"Pollution can hurt the heart and also lead to stroke, [and] people with AFib are especially vulnerable," said Magnani, a cardiologist at the University of Pittsburgh Medical Center.
For their research, Magnani and his colleagues analyzed the health data on 31,414 adults treated for AFib in the University of Pittsburgh health system between 2007 and 2015. Roughly half of the patients were female, and all ranged in age from 61 to 87.
Of the patients included in the analysis, 1,546 suffered an ischemic stroke during the study period, the researchers said.
Those with the highest levels of particulate matter exposure -- between 11.11 and 15.74 micrograms per cubic meter -- were between 20% and 36% more likely to suffer a stroke compared to those with the lowest levels of exposure -- between 9.13 and 10.07 mcg. per cubic meter.
The major components of particulate matter are sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. It consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air, according to the World Health Organization.
For the patients included in the study, average annual particulate matter exposure -- a commonly used measure of air pollution -- was around 10 mcg. per cubic meter, which is equivalent to the WHO's ceiling for healthy air quality.
AFib is an irregular heartbeat that can cause blood clots, stroke, heart failure and other heart-related complications.
About 12 million Americans have the condition, according to the U.S. Centers for Disease Control and Prevention.
"People with any heart condition need to understand that they are at high risk from environmental exposures, [and] they need to monitor pollution levels in their area and pay attention to the air quality," Magnani said.
"People with AFib tend to be older and have ... other [health] conditions, so pollution has an additive effect on [their] risk of stroke," he said.