Study examines ultra-tiny particles produced when things are burned

This article was written by Moira Welsh and was published in the Toronto Star on August 6, 2024.

Ultrafine — and unregulated — air particles from vehicle emissions and industries in Canada’s two largest cities are linked to an estimated 1,100 premature deaths each year, a new study found, with 600 of those deaths in Toronto.

In Toronto and Montreal neighbourhoods near airports or heavy traffic, nanosized particles from burning fuels such as diesel are so small they have escaped significant research and oversight, said a “first of-its kind” study, published in the American Journal of Respiratory and Critical Care Medicine.

Led by researchers at McGill University, the study found that the ultra-fine particles are associated with 7.3 per cent increase in the risk of non-accidental deaths. The paper calls for more study and regulation.

Scott Weichenthal, of McGill, said the particulates examined in the study are “small particles that are produced when you burn things that are not regulated, that can be inhaled deep inside the lungs and get into the systemic circulation that reach all throughout your body.”

Researchers found a “very consistent” relationship between the ultra fine particles and premature mortality, said Weichenthal, an associate professor in McGill’s Department of Epidemiology, Biostatistics, and Occupational Health.

“Where you live determines how much of this exposure you have. And people who are more exposed to these kinds of particles die sooner from non-accidental mortality but also cardiovascular mortality, respiratory mortality and cancer mortality,” he said.

Respiratory deaths accounted for the highest increase in mortality, at 17.4 per cent, followed by a 9.4 per cent rise from coronary artery disease, the study found.

The ultrafine particulates, for example, have an adverse effect on blood vessels, contributing to coronary artery disease, he said. The paper noted that these particles also “contribute to oxidative stress and trigger inflammation leading to possible tissue damage, DNA modification and disruption of cell growth.”

Environmental regulations have reduced air pollution in North America, researchers say, but are not controlling the ultrafine particles. In New York, the study said that the ultra fine particulate levels have risen, even as the larger particulate levels have dropped.

The size of these tiny particle is important when considering health impacts, since earlier studies that did not take the particle size into account and may have missed or underestimated serious health risks,” a McGill press release said.

As part of the study, the team of researchers from several universities tracked air-pollution levels for a 15-year period starting in 2001. They looked at neighbourhoods that were populated by 1.5 million adults.

“Anytime you burn anything,” said Weichenthal, “it could be gasoline, it could be diesel, anytime you’re burning an organic material, you are increasing these particles.”

‘‘ People who are more exposed to these kinds of particles die sooner from non-accidental mortality.”

SCOTT WEICHENTHAL MCGILL RESEARCHER