Exposure to air pollution has been linked to an increased risk of irregular heartbeat, according to a large study conducted in 322 Chinese cities.
Two common irregular heartbeat conditions, known as arrhythmias, are atrial fibrillation and atrial flutter. These conditions can progress to more serious heart diseases and affect an estimated 59.7 million people worldwide.
While evidence linking air pollution with arrhythmia has been inconsistent, a new study published in the Canadian Medical Association Journal (CMAJ) has found an association between air pollution and an increased risk of these conditions.
To establish this link, Chinese researchers evaluated hourly exposure to air pollution and the sudden onset of arrhythmia symptoms using data from 2,025 hospitals in 322 Chinese cities.
Air pollution levels in China exceed the World Health Organization’s (WHO) guidelines for air quality. The researchers used air pollutant concentrations from monitoring stations nearest to the reporting hospitals for their analysis.
“We found that acute exposure to ambient air pollution was associated with increased risk of symptomatic arrhythmia,” said Dr. Renjie Chen of Fudan University’s School of Public Health in Shanghai. “The risks occurred during the first several hours after exposure and could persist for 24 hours.”
The study included 190,115 patients with the acute onset of symptomatic arrhythmia, including atrial fibrillation, atrial flutter, premature beats, and supraventricular tachycardia, a heart condition that causes an abnormally fast heart rate.
Air pollution was most strongly linked to atrial flutter and supraventricular tachycardia, followed by atrial fibrillation and premature beats.
Among six pollutants, nitrogen dioxide (NO2) had the strongest association with all four types of arrhythmias. The greater 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 wrote.
“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.”
The authors emphasized the immediate nature of the association and the need to protect at-risk individuals during periods of 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 concluded.
Air pollution is also a serious issue in Europe, where it kills more than 1,200 children and teenagers each year, according to the European Environment Agency (EEA).
In a recent report, the EEA warned that air pollution significantly increases the risk of disease later in life. Despite improvements in recent years, levels of key air pollutants in many European countries remain “stubbornly above” WHO guidelines.
Younger people are particularly susceptible to air pollution because their bodies and immune systems are still developing. The report estimated that air pollution causes more than 1,200 premature deaths each year among individuals under 18 across the EEA’s member countries, which do not include the UK or Switzerland.
