Editorial Archive

Safety Notice #2: Subway Air Quality – Health Canada Study – Update

4/27/17 6:12 PM

From the Safety and Environment Department

On April 25, a study by Health Canada on TTC air quality was published in a scientific, peer-reviewed academic journal. The study was conducted to compare dust exposures between major transit properties in Canada to help guide transportation planners in Canada to improve air quality for commuters. The purpose was to gather information about dust levels, not to draw conclusions about the impact of the dust levels on health. The study confirmed previous internal assessments that found that the dust is primarily iron from steel wheels and rails, and that it is dustier in an enclosed subway tunnel than outside. On April 26, there were three 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.

After reviewing the detailed analysis of dust exposures from Health Canada, the Ontario Ministry of Labour ruled the air in the subway was “not likely to endanger”. The Ministry of Labour Occupational Hygienists reviewed the Health Canada study data and explained that all metal dust levels (including iron and manganese), extrapolated for eight hour exposures, would be well below (less than 10 per cent) of their respective occupational exposure limits. This information is consistent with existing TTC exposure data and is applicable for all workers in the subway. The Ministry’s ruling confirmed that the TTC met all of its legal and due diligence obligations and the conditions within the subway didn’t warrant employees wearing masks. In other words, the air quality in the subway system is safe and personal protective equipment related to air quality is not required.

Today, Health Canada wrote to the TTC to clarify reports that results of the study were never designed as a statement of health impacts of air quality in the subway system. The letter, in part, reads,

“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. Air quality in Beijing is often at levels much higher than that observed in Toronto subways during peak transit hours. Peak levels of air pollutants (particulate matter) in Beijing are often up to 8 times higher than the levels measured in the Toronto subway, and can last over periods of several days.

“In addition, there have been numerous studies of air quality in subway systems internationally, including those in London, New York, and Stockholm, and the results from Toronto are consistent with levels observed elsewhere.”

TTC CEO Andy Byford said, “It’s most regrettable that a comparison to the air quality on the TTC was made, in some media articles, to that of Beijing, one of the planet’s most polluted cities. 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.”

In addition, new subway trains and refurbishment of HVAC systems on older subway trains have helped mitigate and reduce particulate matter on trains. A new vacuum car with a HEPA filter – a gold standard for air filtration – will arrive on TTC property later this year, furthering the TTC’s commitment to a healthy and safe public transit system.

The TTC remains a safe system for our customers and employees.

If you have any questions, please contact me at 416-393-4229.

John O’Grady
Chief Safety Officer
Safety and Environment Department
April 27, 2017

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