A shift to cleaner transportation could prevent more than 3,600 premature deaths in Montreal and Toronto by reducing ultrafine particle pollution, finds a new study led by McGill researchers.

Ultrafine particles (UFPs) are microscopic pollutants produced in large quantities by vehicle exhaust. Because of their small size, they can penetrate deep into the lungs and bloodstream and may contribute to serious health problems such as heart and lung disease.

“Most Canadians are exposed to UFPs on a daily basis and these pollutants are not currently regulated, despite growing evidence linking them to increased mortality risk,” said lead author Marshall Lloyd, Research Associate in McGill’s Department of Epidemiology and Biostatistics.

While air quality regulations have reduced many pollutants, ultrafine particles are not currently regulated, he added.

The researchers modelled how different policies would change UFP levels, drawing on real emission and climate plans in Toronto and Montreal, including targets for electric vehicle adoption. Using established population and health data, they then estimated how those changes could translate into reductions in premature deaths between 2021 and 2040.

The results indicate the most ambitious scenario could prevent about 1,100 premature deaths in Montreal and more than 2,500 in Toronto, totalling over 3,600 across both cities. It combined:

• rapid electric vehicle adoption (reaching about half of all vehicles by 2030 and nearly 100 per cent by 2040)
• accelerated retirement of older, heavy-duty vehicles, particularly pre‑2007 diesel trucks
• reduced overall traffic levels

“Even without more electric vehicles on the road, we found that keeping traffic levels steady and retiring older heavy-duty diesel trucks could still prevent over 3,300 UFP-related deaths across both cities,” said senior author Scott Weichenthal, Professor in McGill’s School of Population and Global Health.

Cleaner air from reduced vehicle emissions would have the greatest impact in neighbourhoods with higher proportions of low-income households, immigrants and visible minorities, which are often located near major roads, he added.

About the study

“Estimating reductions in premature mortality attributable to outdoor ultrafine particles with increasing prevalence of electric vehicles and 2 other tailpipe-related emissions reduction scenarios” Marshall Lloyd and Scott Weichenthal et al., was published in Environmental Science & Technology. The study was supported by the Natural Sciences and Engineering Research Council of Canada.