Tens of thousands of runners braved the cold and pollution to take part in a fitness fun run despite calls for it to be halted over health fears, Yangcheng Evening News reports.

Internet users campaigned that the run, organized by the local sports bureau to improve people's wellbeing in Lanzhou, Gansu province, was actually a health risk due to the lingering smog.

"I'm a father. Common sense tells me that such severe air pollution does not suit outdoor activities. Let alone racing around the city," one man wrote on his micro blog.

Students race on in Lanzhou despite the air pollution on Jan 1, 2012. [Photo/CFP]

His appeal was echoed by many online.

Columnist Wang Pei expressed "astonishment" writing, "As a severely polluted city, Lanzhou does not suit running at all. This race is more absurd and evil than locking students in a smoking area reading."

But the objections did not stop the race going ahead with more than ten thousand taking part. The oldest was aged 86 and the youngest seven.

Lanzhou suffers bad air quality in winter due to coal being used for heating. On Jan 1, the city had a pollution index of 216, which is classed as medium pollution, according to data released by Lanzhou environmental authority.