Long-term exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) is independently associated with greater coronary artery calcium, higher total plaque burden, and more obstructive coronary artery disease on cardiac CT, researchers have reported.
The strongest effects of this exposure is seen in women, even at the moderate pollution levels typical of high-income countries, according to a team led by Kate Hanneman, MD, of the University of Toronto. The findings were published June 9 in Radiology.
"Even at exposure levels below current Canadian air quality standards, long-term air pollution was independently associated with more advanced coronary artery disease -- suggesting air pollution belongs alongside blood pressure, cholesterol, and smoking as a modifiable cardiovascular risk factor," she said in an RSNA statement.
Air pollution is the leading environmental risk factor for cardiovascular disease globally, contributing to roughly 2.5 million cardiovascular deaths each year, Hanneman and colleagues noted. Previous studies have shown that short-term air pollution exposure (that is, hours to days) is associated with increased emergency department visits for ischemic heart disease, hospital admissions for heart failure, and greater use of medical imaging, while exposure over the longer term (that is, months to years) has been linked to higher risk of myocardial infarction, stroke, and cardiovascular mortality.
Hanneman and colleagues conducted a study that included 11,128 adult patients who underwent outpatient cardiac CT for coronary artery disease (CAD) evaluation between January 2012 and December 2023 (of the total cohort, 51.7% were men and 7,313 underwent coronary CT angiography [CCTA]). They evaluated study participants' coronary artery calcium score (CACS), total plaque burden, and presence of obstructive CAD (defined as equal to or greater than 70% diameter stenosis). The group assessed mean exposure to PM2.5 (equal to or greater than 2.5 μg/m³) and NO2 air pollution (parts per billion, or PPB) over the 10-year period before cardiac CT; it found that median 10-year exposure for PM2.5 was 7.5 μg/m³ and for NO2 13.4 PPB.
The investigators reported the following:
- Greater PM2.5 and NO2 exposures were associated with greater CACS (incidence rate ratio, 1.11 for PM2.5, p < 0.001, and 1.01 for NO2, p = 0.04).
- Greater PM2.5 and NO2 exposures were associated with greater total plaque burden (odds ratio for PM2.5, 1.13, p = 0.02, and for NO2, 1.04, p < 0.001).
Significantly, they also found that women were more affected by long-term air pollution exposure, with higher odds ratios of obstructive CAD for both PM2.5 and NO2 (OR 1.81, p = 0.048 and OR 1.06, p = 0.04 respectively). There was no evidence of this association in men.
![Axial images from unenhanced calcium score cardiac CT (left) and curved planar reformation images from CT angiography (right) show that higher long-term exposure to air pollution is associated with greater coronary artery calcium and more obstructive coronary artery disease (CAD). Top row: Images in a 68-year-old male patient with higher 10-year mean ambient air pollution exposure (7.9 μg/m3 for particulate matter measuring ≤2.5 μm in diameter [PM2.5] and 17.4 parts per billion [ppb] for NO2) with extensive CAD (coronary artery calcium score [CACS] >1,000 and obstructive CAD [≥70% diameter stenosis]). Bottom row: Images in a 57-year-old female patient with lower 10-year mean ambient air pollution exposure (6.3 μg/m3 for PM2.5 and 4.6 ppb for NO2) with no CAD (CACS = 0 and no obstructive stenosis).](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/06/hanneman.r6SMLzkezo.png?auto=format%2Ccompress&dpr=2&fit=max&q=70&w=700)
Axial images from unenhanced calcium score cardiac CT (left) and curved planar reformation images from CT angiography (right) show that higher long-term exposure to air pollution is associated with greater coronary artery calcium and more obstructive coronary artery disease (CAD). Top row: Images in a 68-year-old male patient with higher 10-year mean ambient air pollution exposure (7.9 μg/m3 for particulate matter measuring ≤2.5 μm in diameter [PM2.5] and 17.4 parts per billion [ppb] for NO2) with extensive CAD (coronary artery calcium score [CACS] >1,000 and obstructive CAD [≥70% diameter stenosis]). Bottom row: Images in a 57-year-old female patient with lower 10-year mean ambient air pollution exposure (6.3 μg/m3 for PM2.5 and 4.6 ppb for NO2) with no CAD (CACS = 0 and no obstructive stenosis).RSNA
"Our findings support considering environmental exposure as part of a patient's cardiovascular risk picture, and they show that the cardiac CT we already perform can capture subclinical disease linked to air pollution exposure," Hanneman told AuntMinnie.com. "The larger implications are at the population level. The results add to evidence that reducing long-term air pollution exposure could meaningfully protect cardiovascular health, and because fossil-fuel combustion drives both air pollution and greenhouse-gas emissions, cleaner air carries a direct climate co-benefit."
In any case, imaging is a "powerful and underused tool for studying environmental contributors to disease," Hanneman explained, noting that "cardiac CT allows us to visualize and quantify the cardiac effects of long-term air pollution across a large population, and the same approach could be applied to other exposures and outcomes."
"This is an area where radiology has a real opportunity to contribute to both environmental health research and the broader conversation about planetary health," she concluded.
Read the study here.
