- The risk of arrhythmia appeared to spike within a few hours of being exposed to heavy air pollution before dissipating after 24 hours.
- The report adds to evidence suggesting that air pollution can damage the cardiovascular system.
- Scientists suspect that harmful chemicals in the air cause stress and inflammation, which can impair heart function.
The risk of arrhythmia, or irregular heartbeat, appears to be elevated after even relatively brief exposure to heavy air pollution, according to new research.
The study, published in the Canadian Medical Association Journal Monday, evaluated how hourly exposure to air pollution across China, an area that has consistently high levels of air pollution, was associated with arrhythmia.
To understand the link between air pollution exposure and arrhythmia, the researchers analyzed hourly air pollution concentration levels and, using health data sourced from 2,025 hospitals in 322 Chinese cities.
Over 190,000 patients with acute onset of symptomatic arrhythmia — including atrial fibrillation, atrial flutter, supraventricular tachycardia, and premature beat — were included in the evaluation.
Six different types of air pollution were assessed: fine particles (PM2.5), coarse particles (PM2.5–10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO) and ozone.
The team found that the risk of arrhythmia increased substantially within the first few hours of exposure to air pollution, then lessened after 24 hours.
Air pollution was most strongly associated with atrial flutter and supraventricular tachycardia, followed by atrial fibrillation and premature beats.
The associated risk was most notable among males, which the researchers suspect may be due to a greater prevalence of risk factors for arrhythmias like smoking and alcohol consumption and more exposure through outdoor activities, including work.
The associations were also greatest during colder seasons, which is likely because cooler temperatures may intensify air pollution’s impact on the cardiovascular system.
The researchers also found that nitrogen dioxide (NO2) had the strongest association with all types of arrhythmia — the more NO2 people were exposed to, the stronger the association.
Dr. Jon Samet, MD, MS, a pulmonary physician, epidemiologist, and dean of the Colorado School of Public Health at the University of Colorado Anschutz Medical Campus, says the findings add to prior research that shows air pollution is well-established as a cause of morbidity and mortality from heart disease.
“There has been a great deal of work on air pollution and serious heart rhythm disturbances, for example in patients with implanted defibrillators. Air pollution affects the variability of the heart rate rhythm,” Samet said.
The risk of arrhythmia appeared to spike within a few hours of being exposed to heavy air pollution before dissipating after 24 hours.
Though prior studies linking short-term air pollution exposure to arrhythmia have been inconsistent, this new report adds to evidence suggesting that air pollution can damage the cardiovascular system and potentially contribute to an irregular heartbeat.
The researchers hope their findings highlight the need to reduce air pollution and encourage at-risk individuals to protect themselves during periods of thick air pollution.
“We know that exposure to chronic air pollution does impact the heart,” Dr. Mary Prunicki, MD, Ph.D., the director of air pollution and health research at the Sean N. Parker Center for Allergy & Asthma Research at Stanford Medicine, says.
There’s a well-established link between air pollution and atherosclerosis, a buildup of plaque in the coronary artery that can diminish heart health.
“This buildup of calcium can restrict blood flow to the heart and other major blood vessels —increasing the likelihood of cardiovascular events like heart attack and stroke,” Prunicki told Healthline.
Scientists are investigating why air pollution may have this effect on heart rhythm, but some suspect that harmful chemicals in the air cause oxidative stress and systematic inflammation, which can impair heart function.
Air pollution may also exacerbate pre-existing arrhythmias.
According to Prunicki, arrhythmia can increase the risk for blood clots and strokes leading to sudden death and heart failure.
“These are arrhythmias that would need treatment, perhaps on an emergency basis if sustained,” says Samet.
It’s unknown how much air pollution is too much, however, Prunicki says we’ve seen cardiac effects, like increased blood pressure, in areas where air pollution levels are below the criteria cutoff levels.
More research is needed to determine why air pollution has this effect on heart health, how different concentrations of air pollution affect cardiac function, and if exposure at a young age increases the risk of future cardiac issues.
“We have ample evidence from this type of study on heart arrhythmias. I would like to see more studies on the mechanisms by which air pollution has these effects,” Samet said.
The risk of arrhythmia appears to be elevated after even relatively brief exposure to heavy air pollution. That risk spikes within a few hours of being exposed to heavy air pollution before dissipating after 24 hours. The researchers hope their findings highlight the need to reduce air pollution and encourage at-risk individuals to protect themselves when air pollution is heavy.