The IMA had urged the Delhi High Court to call off the marathon following a jump in pollution levels since November 6, which doctors had termed as a health emergency. Doctors had warned that running in severe pollution can trigger asthma attacks, worsen lung conditions and increase the risk of heart attacks and strokes. They requested people not to venture outdoors if there was no pressing need.
The Delhi government had also likened the city to a "gas chamber", but couldn't implement its preferred odd-even vehicle rationing arrangement following rejection of its request for exemptions granted to women and two-wheelers by the National Green Tribunal.
Last week, telecoms giant Airtel had threatened to pull its sponsorship of the event if the Delhi government failed to act to improve the city's air quality.
The organisers of the half marathon, however, said that they would go ahead with the event despite warnings that the event could harm the health of the runners. On Thursday, the Delhi High Court gave a green signal to the marathon as pollution levels showed a slight drop.
International elite athletes, including world champion marathoner Geoffrey Kirui and 10,000m Olympic gold medallist Almaz Ayana, had brushed aside concerns of pollution, saying they would run the Delhi Half Marathon which made its debut in 2005.
"I am feeling all right. Everybody is going to run and I am also going to run. I am not concerned about this (pollution)," Ayana, who broke the world record in women's 10,000 m race during her gold-winning feat in Rio Olympics, had said ahead of the half marathon.
Kenyan runner Kirui added, "I have come here for the race, that means I am not going to be bothered by the talks of pollution in Delhi. I ran here last year also and there is this talk of pollution. I am all right, not thinking about this pollution. I am now focussed on Sunday's race."
On Saturday, pollution levels in the city rose slightly after a small dip due to light showers a day before. The Central Pollution Control Board (CPCB) recorded the air quality index (AQI) of Delhi-NCR at 301 and 308 in Delhi at 7 pm on Saturday. The air quality is expected to remain "very poor" for at least the next three days.
In its preparation, the track was sprayed with salt mixed in effluent treated water. The elaborate arrangement for the run included, six medical stations, 75 doctors, 50 physiotherapists, over 100 nurses, and 12 water stations. Nebulisers, a device that helps change liquid medicine into a fine mist so that the patient can breathe easily, were provided and ambulances equipped with oxygen tanks were on standby along the route during the marathon.
However, it wasn't easy running through the visible morning haze and some runners were seen wearing face masks.
"My eyes burnt, my throat was dry. I have a runny nose now. It's been terrible since I landed here yesterday," said Rohit Mohan, 30, from Bangalore who wore a mask during the half marathon.
Another runner Sitam said that even after health warnings, he decided to run because he wanted to "send a message to the government to do something for fitness enthusiasts and ensure a pollution free environment".
(With inputs from agencies)