Toronto’s subway had the highest level of particulate matter in the air, consisting mostly of microscopic dust particles of iron and maganese from abrasion of the metal wheels and tracks.

Toronto’s subway had the highest level of particulate matter in the air, consisting mostly of microscopic dust particles of iron and maganese from abrasion of the metal wheels and tracks. Since the study was done, Toronto has been initroducing new models of cars with better HVAC systems inside the wagons.
Photo Credit: Mike Wise- via CBC

Toronto subway air quality: as bad as Beijing

A study of the three metropolitan subway systems in Canada’s three major cities shows some surprising results.

The systems were tested in Vancouver on the west coast, and in Toronto and Montreal in central Canada.

The findings were published in the science journal “Environmental Science & Technology” under the title, “Metro Commuter Exposures to Particulate Air Pollution and PM2.5-Associated Elements in Three Canadian Cities: The Urban Transportation Exposure Study” (HERE)

Toronto Mayor John Tory, (left), and Prime Minister Justin Trudeau, (right,) use power tools on a TTC subway car undercarriage at the Greenwood Subway Yard in Toronto on May 6, 2016 at a media event. Microscopic particles from the steel wheels and rails are being wafted into the air at subway stations and in the wagons. © Nathan Denette/Canadian Press

The study was a collaboration with the federal agency Health Canada, McGill University in Montreal, and the University of Toronto.

The study conducted in 2010 and 2011 found the subway system in Toronto had particulate matter some ten times higher than outside.

Toronto subway levels were three times higher than Montreal’s while Vancouver’s “sky train” which travels outside in some areas, had the lowest levels.

Greg Evans, a University of Toronto engineering professor, investigated air pollution in the city’s subway lines and found it was the highest of any of Canada’s three major transit systems.
Greg Evans, a University of Toronto engineering professor, investigated air pollution in the city’s subway lines and found it was the highest of any of Canada’s three major transit systems. © Tyler Irving

Some of the particles measured are known as PM 2.5, having a size of 0.00025 cm.

These can easily get into the lungs and potentially cause damage.

The study found on average 100 micrograms of pollutant per cubic metre in Toronto,  University of  Toronto engineering professor Greg Evans says that is similar to particulate on a typical day in Beijing,

A lot of the microscopic particles were metallic, iron and manganese.   “We believe a lot of the particles that we detect in the air come in because of the abrasion of the wheels on the tracks”, said Evans.

Montreal’s metro uses rubber tires. The older trains (shown here) have begun to be replaced by newer models.
Montreal’s metro uses rubber tires running on cement pads. The older trains (shown here) have begun to be replaced by newer models. © CBC

Montreal’s system which uses rubber tires and a combination of electro-magnetic braking and wooden brake pads.  It registered  a particulate level of 36 micrograms per cubic metre, while Vancouver even though it has steel wheels and rails like Toronto, registered an average of 17 micrograms per cubic metre. This was due to the fact that 80 percent of the system is above ground and exposed to the air.

Montreal’ metro uses rubber wheels on both the older cars now slowly being phased out, and on the newer cars. Both have large *road* wheels and smaller side wheels which keep the cars centres on the track © CBC

The study noted that with average commute times of an air, a sizeable portion of the population is exposed to the dust, contributing to 20 percent of a Toronto rider’s exposure, and 11 percent in Montreal and Toronto.

Vancouver’s *Sky train* uses steel wheels and rails, but has a low level of airborne pollutants as it runs 80 percent above ground. © Tina Lovgreen/CBC)

The Toronto Transit Commission says since the study they have taken measures to improve air quality including a giant vacuum cleaner that travels the rails sucking up some of the settled dust on the tracks and better HVAC systems on the new model of train. Montreal has also begun introducing a new model of train.

Evans says the study can be used  to make improvements in all systems going forward.

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2 comments on “Toronto subway air quality: as bad as Beijing
  1. Avatar Dale C Rubin says:

    Very amazing Article about air quality thanks for sharing this stuff i liked it and will use this useful information for my research papers

  2. Avatar Herry says:

    Whaddaya know, ANOTHER reason not to go to Hogtown !!!!!!!!! Ever !