Study: High Long-Term Exposure to Fine Particulate Air Pollution is Associated With Diffuse Myocardial Fibrosis

High long-term exposure to ambient fine particulate air pollution is associated with early signs of heart damage, according to recent data published in Radiology. Specifically, the authors observed that this particulate matter in the air, known as PM2.5, can contribute to diffuse myocardial fibrosis, a form of scarring that can precede heart failure.¹

Image credit: DimaBerlin | stock.adobe.com

Cardiovascular disease is the leading cause of death worldwide, according to the authors. Cleveland Clinic estimates that almost half of US adults have at least 1 form of heart disease. Treatment or prevention methods can involve pharmacologic methods or lifestyle modifications, such as exercise, dietary changes, and smoking cessation.^1,2

“We know that if you’re exposed to air pollution, you’re at higher risk of cardiac disease, including a higher risk of having a heart attack,” study senior author Kate Hanneman, MD, MPH, department of medical imaging at the Temerty Faculty of Medicine, University of Toronto, and University Health Network in Toronto, said in a news release. “We wanted to understand what drives this increased risk at the tissue level.”³

To determine the association between long-term exposure to ambient fine particulate matter with a 2.5-µm or smaller aerodynamic diameter (PM2.5)—which is commonly from vehicle exhaust, industrial emissions, and wildfire smoke³—as well as the extent of diffuse myocardial fibrosis that is quantified with cardiac MRI, the investigators conducted this single-center, retrospective study. Patients with dilated cardiomyopathy (DCM) or controls with normal cardiac MRI findings from January 2018 to December 2022 were included. Diffuse myocardial fibrosis was quantified using cardiac MRI native T1 mapping z-scores. Further, residence-specific ambient PM2.5 concentration was assessed as the mean of daily exposure concentration in the year prior to cardiac MRI using direct measurements from the nearest monitoring station. For clinically relevant covariates, multivariable models were adjusted if necessary.¹

For this study, a total of 201 healthy controls and 493 patients with dilated cardiomyopathy were enrolled. Most of the patients were men (n = 443), and the mean age was about 47 ± 16 years. Multivariable models demonstrated that each 1-µg/m³ increase in 1-year mean PM2.5 exposure was correlated with a 0.30 higher native T1 z-score in patients with DCM (adjusted β coefficient: 0.30 [95% CI 0.13–0.47]; P < .001) and a 0.27 higher native T1 z-score in controls (adjusted β coefficient: 0.27 [95% CI 0.04–0.51]; P = .02). Regarding absolute values, each 1-µg/m³ increase in 1-year mean PM2.5 exposure was associated with 9.1 msec higher native T1 at 1.5 T (β coefficient: 9.1 [95% CI 2.04–15.97]; P = .01) and 12.1 msec higher native T1 at 3 T (β coefficient: 12.1 [95% CI: 5.74–18.52]; P < .001).¹

Further, the stratified models indicated the largest effect sizes for the association of PM_2.5 exposure with native T1 z-scores in women (β coefficient: 0.49; 95% CI: 0.23, 0.76; P < .001), smokers (β coefficient: 0.43; 95% CI: 0.02, 0.84; P = .04), and patients with hypertension (β coefficient: 0.48; 95% CI: 0.16, 0.80; P = .004).¹

“Even modest increases in air pollution levels appear to have measurable effects on the heart. Our study suggests that air quality may play a significant role in changes to heart structure, potentially setting the stage for future cardiovascular disease,” Hanneman said in the news release. “Public health measures are needed to further reduce long-term air pollution exposure. There have been improvements in air quality over the past decade, both in Canada and the United States, but we still have a long way to go.”³

The authors wrote that knowing a patient’s long-term air pollution exposure history may help refine heart disease risk assessment while addressing the health inequities air pollution contributes to, both in level of exposure and effect. For example, if an individual works outside in an area with poor air quality, health care professionals can incorporate that exposure history into heart disease risk assessment.^1,3

Additionally, the authors noted that the air pollution exposure levels of the patients within the study were below many of the global air quality guidelines, emphasizing the idea that there are no safe exposure limits. While underlining associations between air pollution and myocardial fibrosis, the study also highlights the important role that imaging can play within research and future clinical developments.^1,3

“Medical imaging can be used as a tool to understand environmental effects on a patient’s health,” Dr. Hanneman said. “As radiologists, we have a tremendous opportunity to use imaging to identify and quantify some of the health effects of environmental exposures in various organ systems.”³

REFERENCES

1. Du Plessis J, DesRoche C, Delaney S, et al. Association between Long-term Exposure to Ambient Air Pollution and Myocardial Fibrosis Assessed with Cardiac MRI. Radiology 2025;316:1. doi:10.1148/radiol.250331

2. Cleveland Clinic. Cardiovascular Disease. Accessed July 2, 2025. https://my.clevelandclinic.org/health/diseases/21493-cardiovascular-disease

3. Radiological Society of North America. Exposure to air pollution may cause heart damage. News release. July 1, 2025. Accessed July 2, 2025. https://www.eurekalert.org/news-releases/1088736