The London Subway Is Bad for Commuters' Lungs

"If you find yourself wheezing as you wander down a fume-filled London street, just remember that things could be worse," writes Feargus O'Sullivan. "You could be on the city’s subway system."

"According to a new study from the University of Surrey, London’s Tube riders experience worse air than those who travel by car," adds O'Sullivan. "In the worst cases, particulate levels in the subway system can be as much as eight times higher than those experienced by drivers."

The culprit of the pollution issue in the London Subway isn't the motor or exhaust of the trains—it's from "mechanical abrasion between rails, wheels and brakes."

O'Sullivan provides a lot more detail and context for the study, including listing two big lessons to takeaway.