Fifteen cities in the world have air pollution so bad that 60 minutes of daily cycling outweighs the benefits of exercise. By measuring the annual levels of PM2.5 pollution (tiny particles that embed themselves deep in the lungs) which are created mainly by vehicles and factories, scientists modeled the health effects of active forms of travel and air pollution. No U.S. or European city is included in these 15 cities.
PositiveTip: Choose to exercise outdoors at the time of day when air pollution is at the lowest levels.