Exposure to passive smoking or secondhand smoke — even at small amounts — is associated with a greater risk of a serious heart rhythm disorder, a new study revealed on Sunday.

According to the study presented at the European Heart Rhythm Association EHRA 2024, a scientific congress of the European Society of Cardiology (ESC), once exposed to passive smoking, the odds of developing ‘atrial fibrillation’ begin to increase, with the risk escalating significantly as the exposure time lengthens.

Atrial fibrillation is the most common heart rhythm disorder globally, and the symptoms include palpitations, shortness of breath, fatigue, and difficulty sleeping.

“The dangers of secondhand smoke were significant regardless of whether individuals were at home, outdoors, or at work, indicating that exposure universally elevates the risk of atrial fibrillation,” said study author Dr Kyung-Yeon Lee of Seoul National University Hospital, South Korea.

The study examined the link between secondhand smoke exposure and the long-term risk of incident atrial fibrillation. It included adults aged 40 to 69 years. A total of 400,493 adults were included in the analysis.

Researchers categorised participants into two groups — ‘exposed group’ and ‘non-exposed group’.

The group exposed to secondhand smoke had a six per cent higher risk of incident atrial fibrillation during follow-up compared with the non-exposed group, the study found.

According to the researchers, a dose-dependent relationship was observed, whereby each increase in the duration of weekly passive smoking was linked with an even greater risk of atrial fibrillation.

For example, 7.8 hours of passive smoking per week was associated with an 11 per cent higher likelihood of heart rhythm disorder compared with no passive smoking. The risk of atrial fibrillation for passive smokers was raised in homes, workplaces, and outside spaces, the researchers explained.

“The finding that passive smoking is harmful not only in enclosed indoor spaces but also in outdoor environments underscores the importance of smoking bans to protect public health,” said Dr Lee.