Study comparing subway air quality to Beijing caused 'unnecessary alarm,' TTC charges

The Toronto Transit Commission is firing back after a report on the air quality in Canada's three major transit systems, released this week, compared the pollution in Toronto's subway system to "a typical day in Beijing." 

"It's most regrettable that a comparison to the air quality on the TTC was, in certain media articles, made to that of Beijing, one of the planet's most polluted cities," the transit agency's CEO Andy Byford said in a release Thursday.

"Doing so, frankly, has caused harm to the TTC's reputation and unnecessary alarm for some TTC employees. The TTC had already committed to its own air quality assessment and will begin that study later this year."

Ministry of Labour rules air 'not likely to endanger'

The study, initiated by Health Canada and published in the journal Environmental Science & Technology, studied air pollutants over three weeks in the summer of 2010 and winter of 2011, and used a metric called PM2.5, which are airborne particles smaller than 0.00025 centimetres.

According to the study's co-author, University of Toronto engineering professor Greg Evans, Toronto's outdoor air quality on a typical day would measure around 10 micrograms of pollutant particles per cubic metre of air. That may rise as high as 30 micrograms on a day of poor air quality.

But on the city's subway platforms and trains, the study found an average of 100 micrograms of pollutants per cubic metre, owing largely to abrasion of the wheels on the tracks — comparable, Evans said, to a day in the Chinese capital.

Byford pointed to a ruling by the Ontario Ministry of Labour, issued Wednesday, which deemed the air in the subway "not likely to endanger" employees.

Health Canada study not meant for conclusions about health

The ministry launched an investigation this week after three separate work refusals by TTC subway operators and one maintenance employee "who felt they should be permitted to wear masks while working in the subway system," the TTC's Thursday release said.

The probe also came after the publication of Health Canada's study results. Ministry of Labour officials were not immediately available for comment Thursday.

But while the air quality study was conducted to compare dust exposures between major transit systems in Canada, the TTC says it was not meant for drawing conclusions about the impact of those levels on health.

In its release, the TTC states that Health Canada wrote to the transit agency Thursday to reiterate that the study results "were never designed as a statement of health impacts of air quality in the subway system."

"While the results of this study have been compared to average air quality in Beijing, it is important to note that this comparison can be misinterpreted when simplified," the release quotes Health Canada as saying.

Beijing's air pollution levels are often much higher than that of peak transit hours on Toronto subways, with pollutants often up to eight times higher than the levels measured on the in the train at their peak.

New measures have helped cut pollution levels, TTC says

The release goes on to say that new subway trains and refurbished HVAC systems on older subway trains have helped to reduce pollution levels. It also points to the 2014 creation of a special cleaning crew to remove debris on tunnel walls, cutting down on airborne dust, as well as a new vacuum car with a HEPA filter, which it says will be in place later this year.

In a statement Tuesday, the TTC said it would 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," the statement read.

The transit agency also said it is planning a broader subway air quality study, because the information it currently has is from 1995.

Meanwhile, the co-author of the study released this week, Greg Evans, said he plans to do follow-up research using data from the newer trains.

"While people may be interested in the fact that the levels are quite high in the subway, the thing that interests me is the opportunities that this presents to actually make the system better for all of us," he said.