TORONTO — Researchers published a study in the June 2026 issue of Radiology linking long-term exposure to common air pollutants to advanced coronary artery disease at levels near or below current regulatory safety limits. The study tracked more than 11,000 adults who underwent heart scans from 2012 to 2023 in Toronto and surrounding areas.

The study estimated long-term pollutant exposure for each participant by linking their residential history to air quality data from the previous decade. The research focused on fine particulate matter and nitrogen dioxide. Fine particulate matter consists of airborne particles small enough to be inhaled deep into the lungs, while nitrogen dioxide is generated primarily by vehicle traffic and fossil fuel combustion. Most participants in the study were exposed to air pollution levels below Canada's annual air quality standards.

As exposure to fine particulate air pollution increased, researchers observed more signs of heart artery disease on scans. Higher exposure to fine particulate matter was associated with increased calcium buildup in heart arteries and more common plaque. Both sexes exhibited more calcium and plaque as pollution increased. Scans displayed similar, though smaller, effects for nitrogen dioxide.

The odds of serious artery narrowing were greater with higher pollution exposure, particularly in women. The association between severe artery narrowing and higher pollutant exposure was not statistically significant in men. Cardiac radiologist Kate Hanneman said, "It may reflect biological differences, such as breathing rates relative to body size, hormone-related inflammatory responses and higher levels of noncalcified, harder-to-detect plaque in women." Hanneman added, "There was no level at which the risk clearly flattened or disappeared."

Adjusting for high blood pressure and cholesterol weakened the association between air pollution and coronary artery disease. Cardiac surgeon Salil Deo stated that individuals at higher risk of coronary artery disease may benefit from staying indoors, utilizing air filtration, or wearing an N95 mask outdoors during episodes of heavy pollution. Deo also said, "There may be no 'floor' at which air quality can be considered entirely safe for the human heart."