The union representing TTC workers has asked for a “immediate” meeting with management following the release of an independent study showing that the air quality levels in the city’s subway system are similar to the air quality in smog-prone Beijing on an average day.
The study, which was published in the journal of Environment Science & Technology on Tuesday, was conducted in 2010-2011 by Health Canada in partnership with the University of Toronto and McGill University. It compared air pollution levels in the Toronto subway system to Vancouver’s SkyTrain and the subway system in Montreal.
Speaking to CP24.com Tuesday, Greg Evans, a University of Toronto engineering professor and co-author of the study, said results from the study indicated that pollutants were highest in the Toronto system.
“There were two parts to the study I found surprising. One that I think is of more interest to people is the concentrations of fine particulate matter (PM2.5)… It was quite a bit higher in the Toronto subway than in the other two systems and that really pointed to the opportunity to find ways to reduce it back down in the Toronto system,” Evans said.
Pollution ten times higher than on street
According to the study, the concentration of fine particulate matter in the Toronto subway system was about ten times higher than what a person would experience out on the street in Toronto.
In a news release issued on Tuesday afternoon, the Amalgamated Transit Union Local 113 said that the study “raises serious health concerns” for its members and raises the question of “what did the TTC know? When did the TTC know it?”
The union said that it would seek further information from TTC management and consult its own expert “determine the health and safety implications for its members.”
“Toronto’s subway workers and riders deserve better from TTC management,” ATU Local 113’s Secretary-Treasurer Kevin Morton said in the press release. “Time and time again, TTC management has resisted the union’s requests for air quality testing on the subway system. Transit workers and riders want to be assured they haven’t been exposed to harmful pollution by simply putting in an honest day’s work or commuting to a job.”
Levels a concern for people with pre-existing conditions
Evans said that most people only spent an hour on the subway a day, so the impact on their total exposure to air pollution is limited.
He noted that the levels could be significant for people with pre-existing medical conditions, though.
“Increasing your overall exposure to particles by 20 per cent over a lifetime is not a big concern because concentrations outside vary by that amount day-to-day. What is more of a concern is that people who may be more vulnerable may have pre-existing medical conditions that being exposed to a high concentration like 100 (PM2.5), which is the concentration that was in the subway system, for an hour can be a trigger.”
The heaviest level of air pollution was found on the subway platform, Evans said. Particulate levels were found to be 40 per cent higher on the platform than inside the subway car.
“The reason for that is if you can imagine you’re a commuter, you’re standing on the platform, you know the train arriving when you can feel the wind coming down the tunnel and the train itself functions like a piston coming down the tunnel,” he said
“It pushes all this air ahead of it and what that air does is it will… start the circulation of dust particles that are already in the subway system and so you get a burst of particles when the train comes into the station.”
Evans said another notable finding was that the particles found in the subway were significantly different than the ones that are found outside on the street.
“The ones in the subway are very metal-rich particles. We don’t know the health associations with those sort of particles so there is more work needed there,” he said.
“The solution though is rather than find out more about those particles is just to reduce the concentration down and that is where I think the biggest finding from the study was. It really suggested a number of positive steps that can be taken to reduce the concentration.”
Study addresses ways to help reduce pollution levels
Evans said there are two ways to help reduce the particulate matter in the subway system.
“One is to remove that dust more effectively so just clean out the subway tunnels at night and that is one that the TTC is exploring. And the second is to figure out where the dust is coming from and see if there is ways to reduce that,” he added.
The replacement of subway cars on the Yonge-University Line may have already improved the air quality in the system, Evans noted.
In a statement released Tuesday, the TTC says it had already started taking steps to improve air quality when the research was being conducting in 2010 and 2011.
“The TTC remains a safe system for our customers and employees and plays a vitally important role in reducing pollution cause by vehicle emissions. This study was not intended to assess impacts on overall; rather it looked at levels of certain commonly occurring particulates and pollution,” the statement read.
Among the list of improvement are the refurbishment of older HVAC systems, the introduction of new trains with newer HVAC systems and the purchase of a tunnel vacuum car with a HEPA-certified filtration system.
“We will continue to work with Health Canada to monitor the steps we are already taking to improve air quality including the impact our mitigation measures have had. That work begins this summer.”
Subway system's design plays role in higher pollution levels:
When comparing the Toronto system to Vancouver, particulate matter along the SkyTrain is significantly lower than Toronto, Evans said, because the majority of the system is outdoors.
“The difference between the Montreal and the Toronto system is really interesting. The Montreal subway runs on rubber wheels not steel wheels and it also uses wooden brakes… I think it is those two main differences, the brakes and the wheels, that cause the concentrations to be quite a bit lower in the Montreal subway,” Evans said.
“It is not that we can switch over the Toronto subway to rubber wheels. It does suggest that it is the braking and the way that the subways are driven can have an influence as well.”
The positive message highlighted in the study, Evans said, is that exposure in the Toronto system can be improved.
“There are steps that we can take, thanks to this study, that can improve the air quality for all of us and there is a large number of people that travel on that subway system so it is important that these steps get taken,” he concluded.
