With a fall in temperature and India's major marathons around the corner, it is peak training season for runners in New Delhi. But the spike in smog, however, is making training difficult for most recreational athletes. Nakul Butta, an ultra-runner and coach, always checks the Air Quality Index before every run. If PM 2.5 is over 400, he recommends that runners should stay indoors. "Around this time of the year we do a lot of indoor running for our shorter runs, and for the longer runs we come out and wear pollution masks," Mr Butta says.
