Despite several improvements, air quality in Toronto’s subway system still falls short of international standards, according to a study from a team of chemical engineering students at the University of Toronto.
“We’ve been interested in subway air quality for over a decade,” said Professor Greg Evans. “On Line 2, air quality has remained about the same, and it’s not great compared to many subway systems around the world,” he said.
As part of the study, six students rode the full length of Line 2, spending about two hours per trip collecting air samples.
They found a mix of particles in the air, including trace metals like copper, chromium, and zinc.
While there’s no official threshold for health impacts, Health Canada advises that levels of particulate matter be kept as low as possible in indoor environments.
Platforms see higher levels of toxicity
Filtration systems on TTC trains help reduce exposure slightly, but researchers say the situation is worse on the platforms.
“Pollutant concentrations on the platforms are about two to three times higher than on the trains,” said Isaac Lo, one of the researchers of the study.
The study’s sample size was small, and researchers say they found no immediate cause for concern for the average commuter.
It could be an issue for those who spend prolonged amounts of time on the subway.
“If someone is vulnerable, they should consider wearing a mask,” said Joyce Wu, a pulmonary function technologist.
For TTC employees, the concern is greater since they are exposed to the particulate for longer periods.
“We know everyone has a responsibility to ensure a safe environment for workers and riders,” said Marvin Alfred, President at Amalgamated Transit Union Local 113, the union representing TTC workers. “In the past, we’ve felt some of those concerns weren’t fully addressed,”
In a statement, the TTC said safety remains its top priority.
“Numerous tests and studies have shown the air quality is safe and improving,” the TTC said. “Air quality in the Toronto subway system is comparable to other systems in North America,”
The TTC has received approval to purchase new trains for Line 2. Evans says newer braking systems on Line 1 have helped reduce airborne pollutants, and he hopes the same improvements are coming to Line 2.
