New research warns air pollution can trigger deadly heart disease

By Stephen Beech

Air pollution can trigger potentially deadly heart disease, warns new research.

Long-term exposure to common air pollutants is associated with more advanced coronary artery disease - with notable differences between women and men, say scientists.

A study of more than 11,000 adults showed that even levels of pollution below or near regulatory standards and typical urban exposures are associated with early signs of heart disease - often before symptoms appear.

Canadian scientists say their findings underscore the importance of improving air quality to reduce cardiovascular disease risk.

Air pollution contributed to an estimated 2.46 million cardiovascular deaths in 2021, suggest figures based on Global Burden of Disease data.

It is one of the greatest environmental risks to health and plays a major role in causing heart attacks and stroke, according to the World Health Organisation (WHO).

The research team used cardiac CT scans to evaluate the relationship between long-term exposures to two common pollutants found in urban air, ambient fine particulate matter (PM2.5) and nitrogen dioxide (NO2).

PM2.5 sources include vehicle exhaust, industrial emissions and wildfire smoke.

Around 30 times thinner than a human hair, the tiny particles can penetrate deep into the lungs and bloodstream.

NO2 is a harmful gas produced mainly by burning fossil fuels in vehicles, power plants and industrial processes.

Study lead author Dr. Felipe Castillo, from the University of Toronto, said: "Even at low exposure levels, air pollution is associated with more plaque in the coronary arteries.

“Overall, higher long-term exposure to air pollution was associated with more coronary artery disease on cardiac CT in both women and men.

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"In women, long-term exposure to fine particulate matter was linked to higher calcium scores and more severe narrowing of the arteries.

"In men, higher long-term exposure to fine particulate matter was associated with higher calcium scores and higher plaque burden.”

Nitrogen dioxide exposure was associated with coronary artery disease in both men and women, according to the findings.

The research team analyzed data from adults who had undergone cardiac CT exams from 2012 through 2023 across three major hospitals in Toronto.

They linked patients’ residential postcodes with air quality data to estimate each person’s average exposure to air pollution over the 10-year period prior to CT.

Three markers of coronary artery disease were assessed: calcium score, total plaque burden and obstructive stenosis, also known as artery narrowing.

For each increase in long-term PM2.5 of 1 microgram per cubic meter, there was an 11% increase in calcium build-up in the coronary arteries, 13% greater odds of more plaque and 23% greater odds of obstructive disease.

Exposure to NO2 showed similar trends, though with smaller effect sizes for every one part per billion increase.

Dr Castillo says further research is needed to understand the exact mechanisms, but believes biological, social, and behavioral differences, along with plaque characteristics, may be contributors to the differences seen in men and women.

Study senior author Professor Kate Hanneman, vice chair of research at the University of Toronto, said: “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.”

The findings were presented at the annual meeting of the Radiological Society of North America (RSNA) in Chicago.