Air Pollution Inside Subway Systems Is Much Higher Than Outside, Study Finds

Posted: Apr 30 2017, 2:25pm CDT | by , in Latest Science News

Air Pollution Inside Subway Systems is Much Higher Than Outside, Study Finds
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Canadian subway system's air qualtiy is 10 times worse than the air outside

Subway systems can increase our exposure to air pollution, according to a new study.

The study, which was initiated by Health Canada, analyzed the pollutant levels on three major metro systems in the country and found Toronto Transit Commission had highest levels of pollutants in Canada.

Air pollution on Toronto Transit Commission or TTC is roughly 10 times worse than the air outside. TTC has three times worse air quality than Montreal’s metro while Vancouver's SkyTrain was rated as the cleanest of any of the Canada’s three studied subway systems.

“We know from analyzing the composition of the particles that it's not just everyday grime. The metal concentrations are very high, and the ratios of manganese to iron are similar to what you see in steel.” Co-author Greg Evans, an engineering professor at University of Toronto said.

The study was conducted for three weeks in the summer of 2010 and the winter of 2011, while air quality was evaluated using a metric called PM2.5 in and around the subway systems. The instrument measures the mass of airborne particles smaller than 2.5 micrometers. Researchers found that Toronto outdoor air pollution on a typical day would be around 10 micrograms per cubic meter of air. That may rise as high as 30 micrograms per cubic meters on a poor air quality day in Toronto. But on the city’s subway platforms and trains the pollution levels could be above 100 micrograms. That’s equal to a typical day in Beijing. The Chinese city has a reputation for horrible air quality.

"The findings are similar to previously published studies conducted in metro systems across the world,” said lead author Keith Van Ryswyk from Health Canada's Air Health Science Division. "The results from the study can be used to help guide transportation planners in Canada to improve air quality for commuters."

According to U.S. Department of State, air pollution above 101 micrograms per cubic meter air is unhealthy and increases the risk of respiratory problems in individuals.

"While larger particles get caught in your nose or throat, these ones can make the twists and turns to be able to get deep down into the lungs.” Evans said.

Meanwhile, TTC authority is considering legal action over newly published research as they believe the finding can cause harm to the subway’s reputation and unnecessary alarm for some employees.

TTC’s CEO Andy Byford says. “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.”

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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