Each time you step on to the subway, you’re joining quite a large crowd of bacteria. How large? Microbiologist Norman R. Pace published a study this week detailing the roughly one billion tiny organisms living in every two cubic meters of air in the transit system–about the amount one person breathes each day.
But don’t be alarmed. Though a billion bacteria may seem like a lot, it’s no more than what you breathe in above ground every day. According to Pace, the only key difference on the train is that “fungus loads are somewhat higher, but there’s also a lot of rotting wood, so that’s not so surprising.”
Nothing the team identified was a known carrier of disease, and many of the organisms seemed to come from the humans who use the train. “Every time you step down, you pressurize the air that’s in your shoe,” Pace told the New York Times as an example. “You stomp down, you squirt out a little warm air, carrying foot microbiology.”
(Photo: absolutewade/Wikimedia Commons)