Long-term exposure to air pollution is associated with an increased risk of arrythmia or irregular heartbeat, according to a large study of 322 Chinese cities. The common arrhythmia conditions atrial fibrillation and atrial flutter, which can progress to more serious heart disease, affect an estimated 59.7 million people globally, the researchers said.
Air pollution is a modifiable risk factor for heart disease, but the evidence linking it with arrythmia has been inconsistent, they said. The researchers evaluated hourly exposure to air pollution and the sudden onset of symptoms of arrythmia using data from 2025 hospitals in 322 Chinese cities.
"We found that acute exposure to ambient air pollution was associated with increased risk of symptomatic arrhythmia," said Renjie Chen, from Fudan University, Shanghai, China.
"The risks occurred during the first several hours after exposure and could persist for 24 hours. The exposure–response relationships between six pollutants and four subtypes of arrhythmias were approximately linear without discernable thresholds of concentrations," Chen said.
The study included 1,90,115 (over 1.9 lakh) patients with acute onset of symptomatic arrythmia, including atrial fibrillation, atrial flutter, premature beats and supraventricular tachycardia.
Exposure to ambient air pollution was most strongly associated with atrial flutter and supraventricular tachycardia, followed by atrial fibrillation and premature beats, the researchers said.
Among six pollutants, nitrogen dioxide (NO2) had the strongest association with all four types of arrythmias, and the greater the exposure, the stronger the association, they said.
"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 said.
"Some evidence has indicated that air pollution alters cardiac electrophysiological activities by inducing oxidative stress and systemic inflammation, affecting multiple membrane channels, as well as impairing autonomic nervous function," they added.
The researchers noted that the association was immediate and underscores the need to protect at-risk people during heavy air pollution. "Our study adds to evidence of adverse cardiovascular effects of air pollution, highlighting the importance of further reducing exposure to air pollution and of prompt protection of susceptible populations worldwide," they added.
