As I write this, a largely uncontained wildfire rages just 25 miles to my east. The Bolt Creek Fire in Western Washington sparked on Saturday morning, and within hours, much of the western half of the state was choking on toxic smoke. The sky glowed with an eerie orange haze. Falling from the sky were pieces of ash so large they looked like confetti. By Saturday evening this past weekend, the Seattle metropolitan area had some of the worst air quality in the world.
We know wildfire smoke is terrible for the human body. For example, evidence shows it can cause cardiovascular problems even in healthy adults. Less is known, however, about how air pollution, like wildfire smoke, affects the cardiovascular system of healthy teenagers.
Research published this week in the Journal of the American Heart Association offers some alarming insight into how quickly air pollution affects teenagers’ cardiovascular systems. The study authors say their results should serve as a warning bell about how dramatically even short exposure to fine particulate matter can affect young, healthy teenagers.
What you need to know first — Sudden cardiac death accounts for roughly 50 percent of all cardiac-related deaths and is responsible for 15 to 20 percent of all deaths in Western countries. Sudden cardiac death is relatively rare in minors, but — according to a 2016 study in the journal Circulation — cardiac arrhythmia is one of the most prominent risk factors for sudden cardiac death in young people.
Fan He, an instructor at Pennsylvania State University’s College of Medicine and one of the researchers on the study, tells Inverse that adolescents who are “still in a critical developmental stage” may respond differently to air pollution exposures than adults, but the research into adolescents, cardiac arrhythmia, and air pollution is scant.
“It is of both scientific and public health interest to understand if air pollution could already impact cardiac function in this early life stage,” he says.
What they did — In particular, the researchers focused on “fine particulate matter,” which are 2.5 microns in size and smaller because they “consist of various types of chemicals and some of them are toxic,” He says. Because of their small size, these particles can penetrate the bloodstream and irritate the lungs and blood vessels around the heart.
Particularly relevant to irregular heartbeats, He says, “PM2.5 particles could disrupt the balance between parasympathetic nervous activity and sympathetic nervous activity. An imbalance between these two branches of the autonomic nervous system could induce irregular heartbeats.”
Researchers focused on two types of irregular rhythms: Premature atrial contractions, which originate in the heart’s upper chambers, are typically asymptomatic but can increase the risk of atrial fibrillation; they are also associated with an increased risk of blood clots and stroke. They also looked at Premature ventricular contractions, which originate in the heart's lower chambers and are associated with heart attack, stroke, heart failure, and sudden cardiac death.
Fe and his colleagues analyzed health data for just over 300 adolescents living in central Pennsylvania. The participants were part of a cohort study conducted between 2002 and 2006, at which time they were between six to 12 years old. That same cohort completed a follow-up study 7.5 years later between 2010 and 2013. During the first study, the participants were healthy when the study began and considered at low risk of cardiovascular conditions.
In the follow-up study, researchers measured the kids' exposure to fine particulate matter for 24 hours while monitoring their hearts through an EKG.
In a statement about the study, the researchers note that “the average PM2.5 concentration measured in the study was approximately 17 micrograms of particulate matter per cubic meter of air (µg/m3) per day, which is well below the health-based air quality standard of 35 µg/m3 established by the U.S. Environmental Protection Agency (EPA).”
What they found — A staggering 79 percent of the participants had at least one irregular heart rhythm during the 24-hour study period. Of those, 40 percent had only premature atrial contractions, 12 percent had had only premature ventricular contractions, and 48 percent had both.
The number of premature ventricular contractions increased remarkably quickly: For each increase of 10 µg/m3 fine particle exposure, researchers noted a 5 percent increase in this type of ventricular contract. This jump occurred within two hours of exposure.
“Air pollution can already adversely impact cardiac health, and may contribute to sudden cardiac deaths, among adolescents even in a ‘clean’ environment,” He says and stresses that improvement in air quality standards may be necessary to reduce air pollution exposure and prevent cardiovascular diseases.
Of course, more research is needed to further the impact of air pollution on “other cardiac biomarkers” because that “may shed light on more potential mechanisms that air pollution impacts cardiac health among youths,” he says.
As climate change makes wildfires and their accompanying toxic smoke bigger and more frequent, the fires will likely affect more locations. Clean air efforts are more important than ever. As this recent study shows, the ramifications of not taking action could have consequences for generations.