Ultrafine Particle Pollution Linked to Higher Death Risk, Canadian Study Says

Vehicles are seen on Highway 401 westbound in Kingston, Ont., on Jan. 11, 2019. The Canadian Press/Lars Hagberg

New data says long-term exposure to ultrafine particles in the air of two of Canada’s largest cities causes 1,100 deaths a year.

A study published in the American Journal of Respiratory and Critical Care Medicine looked at outdoor air pollution levels of ultrafine particles (UFPs) from 2001 to 2016 in Montreal and Toronto neighbourhoods that were home to 1.5 million adults.

A collaboration of McGill University, University of Toronto, Carleton University, University of Ottawa, Health Canada, and Statistics Canada, the study was funded by the U.S. Health Effects Institute.

UFPs come primarily from vehicle emissions and industrial activities, and there are no concentration limits set for them by either the federal government or provincial governments, as have been set for larger fine particles known as PM2.5, researchers noted.

“Ultrafine particles are incredibly small, allowing them to penetrate deep into the lungs and enter the bloodstream,“ said principal investigator Scott Weichenthal. ”Increasing evidence suggests these pollutants may contribute to heart and lung diseases, as well as certain forms of cancer.”

Until now, studies have not examined the impacts of UFPs on mortality in Canada, he said.

The study says long-term exposure to UFPs is associated with a 7.3 percent increase in the risk of non-accidental death. The highest increase was in respiratory deaths, at 17.4 percent, followed by coronary artery disease, at 9.4 percent, the researchers said.

State-of-the-art models were used that combine machine learning methods with ground-level measurements, land use information, and aerial images, according to an Aug. 5 McGill news release.

Researchers estimated the number of the particles in the air at various times and then used statistical methods to calculate the connection between exposure and risk of death.

Weichenthal said particle size is important when assessing health impact, and previous studies that didn’t take that into account might have underestimated or missed serious health risks associated with this factor.

“Our research shows a clear link between long-term UFP exposures and increased mortality risk, underscoring the urgent need for regulatory actions targeting these particles,” Weichenthal said.

He said that, as urban areas continue to grow, addressing air pollution is increasingly crucial for the city dwellers’ health and well-being.

“As outdoor ultrafine particles are not currently regulated, there is great potential for future regulatory interventions to improve population health by targeting these common outdoor air pollutants,” the study concluded.

The study is considered the first of its kind and was led by researchers from McGill.