How Healthy is the Air in Subways?

Culture-Independent Analysis of Aerosol Microbiology in a Metropolitan Subway System(32 page pdf, Charles E. Robertson, Laura K. Baumgartner, Jonathan K. Harris, Kristen L. Peterson, Mark J. Stevens, Daniel N. Frank, and Norman R. Pace, Appl. Environ. Microbiol., Mar. 29, 2013)

Also discussed here : How Gross Is the Air of the NYC Subway, Really?(Henry Grabar, the Atlantic – Cities, Apr 26, 2013)

Today we review some research into the quality of the air found in subways, not just the physical and chemical content, but also the microbiological properties  in a rare glimpse in that direction. Results show that the air quality inside the tunnels closely resembles the outside air quality as a result of a highly efficient exchange of air by the movement of trains themselves called “train-pumping”.  The differences that do exist are interesting: more aerosols made up of tiny metal particles generated by the metal wheels and tracks and skin flakes that are emitted by the people using the subways and generated by convection from their skins- but the density found is no worse than in similar gatherings of people in offices for example. Perhaps the most significant aspect of the study is to predefine the conditions of subway air before the possibility of a terror attack using microbiological substances. All of this is important. as more and more cities turn to Light Rail (LRT) to meet their transit needs in addition to those with Heavy Rail.


To see Key Quotes and Links to key reports about this post, click HERE


2 Responses

  1. The odor of the subway is often distinctive and, depending upon location, unique. The 2nd Ave. station smells like the 2nd Ave. station, and a few other underground stations are signature smells. Generally, though, the subways smell like some combination of the unwashed masses mingled with various bodily odors, the scent of food or garbage and often, if we’re lucky, nothing. But that doesn’t mean we’re not breathing in various microbes, metal dust and other assorted things.

  2. The researchers used a high tech mechanism to collect air at around 300 liters per minute (L/min), a big jump on the previous state of the art, which swallowed 12 L/min. That enabled collecting sufficient volume of air — a couple of cubic meters — to take the bacterial census within 20 minutes, instead of after “hours,” says Pace. And analysis by sequencing is far faster and more thorough then using culture.

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