Scientists make surprising discovery about unexpected factor slowing runners down around the US: 'Is this something that we have to pay more attention to?'

Scientists make surprising discovery about unexpected factor slowing runners down around the US: 'Is this something that we have to pay more attention to?'

For marathoners, every second counts, whether they're hunting for a personal best, a Boston Marathon qualifying time, or a time barrier. A new study finds that there is a new, hidden variable holding runners back from their goals: air pollution. What's happening? Scientific American reported on a study published in the Sports Medicine journal, which found that increases in air pollution slowed the finishing times of marathoners across nine U.S. …