AP
Idalys Ortiz of Cuba (in white) throws Tserenkhand Dorjgotov of Mongolia at the women's judo +78kg heavyweight division finals at the Beijing 2008 Olympics on Friday. Cuba won the bronze.

BEIJING, China (AP):

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.

Breathing freely

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 Bird's Nest stadium.

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 semifinals 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.

The efforts have seen mixed results. Since the measures began in July, Beijing had only a handful of days where the level of particulate matter - tiny dust particles that are the worst pollutant - fell within the range of what the WHO considers healthy.

The Associated Press has been taking independent air samples from the Olympic Green, the primary sports thoroughfare, since mid-July. Readings taken between 3 and 4 p.m. on Friday showed 42 micrograms of particulate matter per cubic metre, down from 97 on Thursday. It was well below the high of 604, set on Sunday.

Biggest concern

Health experts say that breathing polluted air can affect respiratory functions and particularly worsen problems for those with asthma or allergies. The biggest concern has been whether the performances of outdoor endurance athletes, who would be exposed to dirty air for more than one hour, would be adversely affected.

Athletes, including world-renowned distance runner Haile Gebrselassie, an asthmatic who holds the world record in the marathon, opted out of some competitions over concerns about Beijing's smog and heat. Instead of running the marathon, he will compete in the 10,000 metres.

Athletes from the United States and several other countries chose to train far outside Beijing, in some cases in neighbouring Korea or Japan to avoid being exposed to the air pollution.