Healthy teenagers are more prone to irregular heartbeats after breathing in fine particulate air pollution, according to the first major study of its impact on otherwise healthy young individuals. The findings have raised concern among researchers because heart arrhythmias, which can increase the risk of heart disease and sudden cardiac death, appear to be triggered even when air pollution is within common air quality limits. Doctors monitored heart activity and the air breathed by more than 300 healthy US teenagers over 24-hour periods. They found that higher concentrations of fine particles called PM2.5s increased the risk of irregular heartbeats for the next two hours. Similar effects have been found in older adults before. “To the best of our knowledge, this is the first study that reports the association between PM2.5 air pollution and cardiac arrhythmias among otherwise healthy adolescents,” the researchers write in the Journal of the American Heart Association. Vehicle exhausts and combustion in the manufacturing and construction industries are a major source of PM2.5s, or particles smaller than 2.5 microns. Once inhaled, they can reach deep into the lungs and even the blood vessels where they cause inflammation that drives disease. Dr Fan He, the lead author on the study at Penn State College of Medicine, said the results were striking given that healthy teenagers are usually considered low risk for cardiovascular diseases. “Our findings suggest air pollution could trigger arrhythmias and contribute to sudden cardiac death among youth, which are devastating events for their families and larger communities,” he told the Guardian. The researchers examined the impact of particulate air pollution on 322 healthy teenagers about seven years after they enrolled, aged six to 12 years old, in the Penn State Child Cohort study. The participants were given heart monitors and mobile air sampling kits to carry around for 24 hours, regardless of whether they were indoors or outside, sedentary or active. The monitors captured two types of arrhythmia that can make people feel their heart has skipped a beat. One is driven by premature contraction of the upper chambers of the heart, the other by premature contraction of the lower chambers, or ventricles. While they are rarely treated unless they cause symptoms, premature ventricular contractions can raise the risk of heart attacks, stroke, heart failure and sudden cardiac death later in life. According to the report, the risk of premature ventricular contractions within two hours of exposure increased by 5% for every 10 micrograms per cubic metre increase in PM2.5. Dr He said it was “alarming” the effect was seen even at an average daily PM2.5 level of 17 micrograms per cubic metre. In the UK, an average daily level of 35 micrograms per cubic metre is considered low-level pollution. On days of high air pollution in England, hundreds more people are rushed into hospital for emergency care after suffering cardiac arrests, strokes and asthma attacks. But particulate air pollution also drives up rates of lung cancer, by awakening dormant mutations that trigger the growth of tumours. In 2020, the British Heart Foundation estimated more than 160,000 people could die in the coming decade from strokes and heart attacks linked to air pollution. He said better air quality standards would improve heart health in the general population and reduce the burden of other chronic conditions such cancer and lung disease. But in the absence of any improvement in air quality, he suggested people take precautions, especially when pollution is at its worst. “Wearing face masks and avoiding vigorous physical activities on highly polluted days and during rush-hours reduce the amount of air pollution exposure and minimise the associated health risks,” he said.