Long-term exposure to common air pollutants is linked to more advanced coronary artery disease, according to a study involving over 11,000 adults. The research was presented at the annual meeting of the Radiological Society of North America (RSNA).
The study found that even pollution levels below or near regulatory standards and typical urban exposures are associated with early signs of heart disease, often before symptoms appear. This highlights the importance of improving air quality as a means to reduce cardiovascular disease risk.
Air pollution is a significant global health concern. In 2021, it contributed to an estimated 2.46 million cardiovascular deaths worldwide, based on Global Burden of Disease data. The World Health Organization identifies air pollution as one of the greatest environmental risks to health and a major factor in heart attacks and strokes.
Researchers used cardiac CT scans to assess the relationship between long-term exposure to two common urban pollutants: ambient fine particulate matter (PM2.5) and nitrogen dioxide (NO2). PM2.5 originates from sources such as vehicle exhaust, industrial emissions, and wildfire smoke; these particles are about 30 times smaller than a human hair and can reach deep into the lungs and bloodstream. NO2 is mainly produced by burning fossil fuels in vehicles, power plants, and industrial activities.
Data from adults who underwent cardiac CT exams between 2012 and 2023 at three Toronto hospitals were analyzed. Patients' residential postal codes were linked with air quality data to estimate their average exposure over the previous decade. Researchers evaluated three markers of coronary artery disease: calcium score, total plaque burden, and obstructive stenosis (artery narrowing).
The results showed that for each increase in long-term PM2.5 concentration by 1 microgram per cubic meter, there was an 11% rise in calcium build-up in coronary arteries, a 13% higher chance of increased plaque burden, and a 23% greater likelihood of obstructive disease. Nitrogen dioxide exposure had similar associations but with smaller effect sizes for every additional part per billion.
Nitrogen dioxide exposure was linked with coronary artery disease in both men and women.
Study senior author Kate Hanneman, M.D., M.P.H., cardiac radiologist at the University of Toronto and UHN stated: "This is one of the largest studies to link long-term gaseous and particulate air pollution at contemporary exposure levels with multiple markers of coronary artery disease assessed by cardiac CT." She added: "Heart disease is the number one cause of death globally. The results of this study add to the growing body of evidence that air pollution is a modifiable cardiovascular risk factor and reinforce the need for further research to understand why these associations differ between men and women."
Additional co-authors include Chloe DesRoche, M.D., M.Sc., Scott Delaney, Sc.D., J.D., M.P.H., Rachel Nethery, Ph.D., Paaladinesh Thavendiranathan, M.D., S.M., and Heather Ross, M.D., M.H.Sc.
Further research will be needed to clarify mechanisms behind these findings as well as differences observed between women and men.
