New Delhi: Tens of thousands of runners braved smoggy conditions for the Delhi half-marathon on Sunday despite dire health warnings from doctors who wanted the race postponed in the heavily polluted Indian capital.

More than 30,000 people competed in the 13.1 mile (21 km) race despite almost two weeks of hazardous pollution levels that forced schools shut for several days.

The US embassy website Sunday showed levels of the smallest and most harmful airborne pollutants reached 214 — nearly nine times the World Health Organization’s safe maximum.

“My eyes are burning, my throat is dry. I have a running nose,” said amateur runner Rohit Mohan, a 30-year-old from the southern city of Bangalore who was among those donning a mask.

“It’s been terrible since I landed here yesterday.”

The Indian Medical Association had asked the Delhi High Court to postpone the event after a surge in pollution levels that it described as a public health emergency.

However, on Thursday the court said it was satisfied by the organisers’ reassurances that they were doing everything they could to ease concerns, and the race was given the green light.

Most were amateur runners, but there were a handful of world-class athletes including Kenya’s Geoffrey Kipkorir Kirui, winner of this year’s London marathon.

Birhanu Legese of Ethiopia, who won the men’s race Sunday, said the pollution was “not that bad”.

“We were scared. I thought maybe it was going to be bad. They told us because of the pollution we might not run a good race. But we didn’t feel it that much,” he said after the race.

“I would say it was perfect to run.”

Light drizzle in the capital early Saturday eased the toxic highs of last week, but the smog remained around levels considered unhealthy.

As the race progressed Sunday pollution readings climbed above 200 — levels at which active people “should avoid all outdoor exertion”, the US embassy warns.

“But here we are running a marathon,” said Ashish Shakya, 31, who for his part decided not to race because of the unhealthy air and watched from the sidelines in a mask.

“Whatever health benefits we get from running are negated because of the smog. I chose not to run because of the health risks.”

Most participants — mainly local amateur runners — seemed unfazed and ran without masks, ignoring the warnings.

“I know pollution is bad and it can affect my health but I am still participating,” said Sitam, who like many Indians goes by one name.

“I want to send a message to the government to do something for fitness enthusiasts and ensure a pollution-free environment for them.”

Telecoms giant Airtel threatened this month to withdraw its sponsorship of the event if authorities in Delhi failed to act to improve the city’s air quality.

Organisers Procam International conceded “that the state of air quality is not conducive” but rejected calls for the race to be postponed.

The course was sprayed with salted water to keep dust levels down and all traffic barred from nearby roads.

A 2014 World Health Organisation survey found Delhi was the world’s most polluted capital, with air quality even worse than Beijing.

Pollution regularly spikes across north India and Pakistan at this time of year as farmers burn the post-harvest crop stubble and cooler temperatures prevent pollutants from dispersing.