A new study is raising alarm about an invisible form of air pollution in Canada's biggest cities, linking tiny particles from aircraft and traffic to a significant number of early deaths. Researchers at the University of Toronto found that ultrafine particles contributed to roughly 1,100 premature deaths a year across Toronto and Montreal, drawing fresh attention to a threat that often goes unseen.
The research, described as the first of its kind in Canada, focused on ultrafine particles, a form of pollution so small that it is tracked by counting the sheer number of particles in a small volume of air. The study examined how exposure to them affects mortality, with the aim of eventually informing regulations that do not yet exist for this type of pollutant.
The findings pointed to a broad range of health risks. Researchers said they looked at both cause-specific and non-accidental mortality and saw increased risks across the board, including deaths from heart and lung problems, a higher chance of conditions such as lung cancer, and an overall rise in mortality tied to the exposure.
Much of the concern centers on neighbourhoods wedged between major pollution sources. Near Toronto's downtown waterfront, residents live close to both a busy airport and heavily travelled expressways, leaving some sandwiched between aircraft operations on one side and constant car traffic on the other, with little escape from either.
Monitoring in the area showed just how variable the pollution can be. Using a handheld device that counts particles roughly the size of a sugar cube, readings near the airport climbed to around 20,000, far above the 2,000 to 5,000 typically seen in a residential area with few sources, and the numbers fluctuated sharply from one moment to the next.
For residents, the data reflects long-standing worries. Some who live in buildings facing the airport have been raising awareness about local air quality for years, pointing to neighbours dealing with debilitating respiratory problems and other health conditions that they fear may be connected to the air around them.
The Canadian study adds to a growing body of international research. Multiple studies around the world have linked ultrafine particles to respiratory disease, and several have documented elevated levels of the particles around airports. Because the pollutants remain unregulated, the researchers hope their work will help build the case for setting future limits.