Delhi's air pollution problem is worse during the morning discouraging runners for the Half Marathon.
One of the most eagerly-awaited sporting events in the national capital, the Delhi Half Marathon to be held later this month, has a cloud of uncertainty looming over it this year.
Alarmed by the high air pollution levels and thick smog that has engulfed Delhi since last weekend's Diwali celebrations, many people have given up the idea of participating in the November 20 event.
It doesn't help that the problem is worse in the morning when most runners are used to training.
Toxins in the air peak early in the day as cooler, stiller nights bring pollutants closer to the ground and trucks barrelling down roads through the night only add to the pollution.
By the morning, it's not fresh air one is breathing but air full of dust and pollution.
Himmat Rana, a fitness enthusiast who has completed the Iron Man triathlon and run the Delhi Marathon for seven years now, has dropped out this time.
"It's just not possible to train," he said, "My entire group that includes some serious runners has all stopped practicing. One by one everyone dropped out as it's just terrible in the morning and we're some three weeks away from the event."
Mr Rana said some of his group members even tried training with pollution masks on but given the intensity of the run, it is just too uncomfortable.
The particulate matter or soot in the air is so dense it penetrates the respiratory system, making it difficult to breath.
On Saturday, given with pollution levels as high as 13 times the safe limit in some neighbourhoods, Delhi's municipal body closed around 1,800 of its schools.