Pollution concerns evaporated yesterday under a picture-perfect canopy of blue skies and white clouds on the first day of the Olympic Games' signature track-and-field events.

Heavy showers that drenched the city on Thursday cleared away much of the pollution, giving Beijing its first genuinely sunny day since the opening ceremony kicked off a week ago. Temperatures hovered around a comfortable 28 degrees Celsius (82 Fahrenheit) with little humidity and a light breeze.

The heavy haze, along with the heat and humidity, that had shrouded the city for days disappeared, giving spectators and athletes alike a clear view from the 91,000-seat Birds Nest stadium.

drastic measures

Air-quality levels reflected the crystalline skies. Beijing's official air-pollution index was at 17, the lowest recorded since the city undertook drastic measures starting in July to curb emissions of major pollution.

"First day I can breathe freely, it's great," said Australia's Tamsyn Lewis, the world indoor 800-metres champion, who qualified for the semi-finals during the morning. "One of my competitors walking out said it reminded her of Melbourne for the Commonwealth Games, so there you go."

The city's air pollution has been the focus of major concern for months leading up to the Games. Beijing typically has air that is two to three times dirtier than most Western countries. In a major bid to clear up the skies, city officials shut down scores of factories, stopped all construction and removed two million vehicles from the road for a two-month period.