As Beijing's polluted air came close to exceeding levels even the Chinese consider dangerous yesterday, one of the International Olympic Committee's most senior figures dismissed the yellow-grey haze that periodically hangs over the city as mist, and blamed the media for overstating pollution problems.

Air quality in Beijing remains a big cause for concern three days before the start of the games. Members of the US athletics team arrived in the city wearing face masks yesterday and organisers are preparing to postpone or relocate endurance events including the marathon and road cycling if smog levels reach dangerous limits.

But yesterday Arne Ljungqvist, chairman of the IOC's medical commission, said he was confident that pollution would not harm athletes or visitors, and suggested media coverage had created a false impression of pollution levels.

Mike Friedman was among the four track cyclists who apologized on Wednesday for wearing pollution-cutting masks as they arrived in Beijing.

"The mist in the air that we see in those places, including here, is not a feature of pollution primarily but a feature of evaporation and humidity," he told the IOC's annual session. "We do have a communication problem here. Once the misconception has become sort of established in the minds of people, it's not that easy to get the right message through.

"I would not discourage athletes from wearing protection devices if they are concerned, but I do not think it is necessary. I would not wear one whether I was an athlete or not." Two days of haze gave way to sunshine yesterday afternoon, but the official measure of air quality remained close to dangerous levels.

Official readings collated by Beijing's municipal environmental protection bureau yesterday gave an air pollution index (API) of 91 for Beijing as a whole, and 87 at the Olympic stadium. The World Health Organisation regards an API of more than 50 as high, and a reading of 100 or more is considered unsafe. The authorities monitor air quality hourly, including levels of particulates, carbon monoxide and nitrogen dioxide, and take limited readings for ozone.

Ljungqvist said the readings were in line with the WHO's interim targets for developing countries, and that the pollution did not pose a threat to the health of athletes visiting for the Olympics.