Long-term exposure to fine particle pollution quietly scars heart muscle, MRI scans reveal, laying the groundwork for future heart failure.
Canadian researchers found even “safe” levels of PM2.5 boosted myocardial fibrosis in both healthy volunteers and cardiomyopathy patients, especially women, smokers, and people with hypertension.
Air Pollution’s Hidden Cardiac Scars
Breathing polluted air could be doing more harm to your heart than you realize—even if you’re healthy. A new study using advanced cardiac MRI imaging has found that long-term exposure to air pollution is linked to early signs of heart damage, specifically a condition known as myocardial fibrosis. This type of scarring in the heart muscle can develop silently and may set the stage for heart failure later in life.
Heart disease remains the leading cause of death around the world, and poor air quality has long been linked to increased cardiovascular risk. But what exactly happens inside the heart when we breathe polluted air has been less clear—until now.
“We know that if you’re exposed to air pollution, you’re at higher risk of cardiac disease, including higher risk of having a heart attack,” said the study’s senior author Kate Hanneman, M.D., M.P.H., from the Department of Medical Imaging at the Temerty Faculty of Medicine, University of Toronto and University Health Network in Toronto. “We wanted to understand what drives this increased risk at the tissue level.”
MRI Reveals Fibrosis Triggered by PM2.5
To investigate, researchers used cardiac MRI—a powerful, noninvasive imaging tool—to look for signs of damage in the heart tissue. They focused on PM2.5, a type of fine particulate matter found in vehicle exhaust, industrial emissions, and wildfire smoke. These particles are tiny, about 30 times smaller than the width of a human hair, and can travel deep into the lungs and enter the bloodstream.
The study examined 694 people, including 201 healthy individuals and 493 patients with dilated cardiomyopathy, a condition that weakens the heart’s ability to pump blood. The results were striking: higher long-term exposure to PM2.5 was consistently linked with higher levels of myocardial fibrosis in both groups. This suggests that even people without existing heart disease may be at risk.
Notably, the strongest effects were seen in women, smokers, and people with high blood pressure—groups that may be especially vulnerable to pollution’s impact on the heart.
Unmasking High-Risk Groups
The study adds to growing evidence that air pollution is a cardiovascular risk factor, contributing to residual risk not accounted for by conventional clinical predictors such as smoking or hypertension.
“Even modest increases in air pollution levels appear to have measurable effects on the heart,” Dr. Hanneman said. “Our study suggests that air quality may play a significant role in changes to heart structure, potentially setting the stage for future Join the SciTechDaily newsletter.
