Acute exposure to air pollution was associated with an increased risk of arrhythmia – irregular heartbeat – in a large study of 322 Chinese cities published in the Canadian Medical Association Journal. Common arrhythmias, atrial fibrillation and atrial flutter, which can progress to more serious heart disease, affect an estimated 59.7 million people globally.
Air pollution is a modifiable risk factor for heart disease, but until now there has been no clear evidence of a link between smog and arrhythmia risk.
“We found that acute exposure to air pollution was associated with an increased risk of symptomatic arrhythmia,” says Renjie Chen of Fudan University in Shanghai. “The risks occurred in the first hours after exposure and could persist for 24 hours. The exposure-response relationships between 6 pollutants and 4 subtypes of arrhythmias were linear”, so as pollution increases, the risk of arrhythmias increases. Researchers assessed hourly air pollution exposure and sudden onset of arrhythmia symptoms using data from 2025 hospitals in 322 Chinese cities. The study included 190,115 patients with acute onset of symptomatic arrhythmias, including atrial fibrillation, atrial flutter, premature beats (originating in the atria or ventricles of the heart), and supraventricular tachycardia. Exposure to air pollution was most associated with atrial flutter and supraventricular tachycardia, followed by atrial fibrillation and premature beats. Furthermore, among the 6 pollutants, nitrogen dioxide (NO2) had the strongest association with all 4 types of arrhythmias, and the higher the exposure, the stronger the association. “Although the exact mechanisms are not yet fully understood, the association between air pollution and acute onset of arrhythmia that we observed is biologically plausible,” the authors write. “Some evidence has indicated that pollution alters cardiac electrophysiological activities by inducing oxidative stress and inflammation, impairing autonomic nerve function.”
The effect of smog is immediate, underlining the need to protect people at risk in the event of heavy air pollution.
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