Olympic Teams Prepare for the Dirty Air in Beijing

Chinese workers at an Olympic construction site in Beijing. Many nations' teams are taking extraordinary steps to lessen the effects of pollution. (By Oded Balilty -- Associated Press)

In November, he accompanied 11 boxers to the Chinese capital for a competition. On their first morning there, Filiberto said, the men returned from their daily 20-minute training run complaining of burning eyes, coughing, congestion and breathing difficulties. Only six of the 11 boxers ended up feeling well enough to compete.

"In my opinion boxers are probably the finest athletes in the world," Filiberto said. "But they didn't think they could make it three rounds in Beijing." Filiberto and the coaches were so alarmed that they ordered the boxers to jog only in hotel hallways thereafter.

Randall L. Wilber, the U.S. Olympic Committee's senior sports physiologist, has come to Beijing a half-dozen times since March 2006 to study the effects of pollution on athletic performance. He concluded that it could be "huge."

Because athletes' lungs work more efficiently than most people's, he said at a presentation in October, "one of these high-powered athletes going out and exercising not even at their maximum, but going out and exercising for 30 minutes, they get a larger effective dose than you or I sitting in a chair in the park in Beijing for eight hours a day."

Athletes, coaches and medical directors for the teams say the potential effects of Beijing's pollution became apparent to them only during the numerous test events, or "dress rehearsals," that China hosted last year.

While some athletes said they were unfazed by the air, others found that it had a profound effect on their performance.

Jeremy Horgan-Kobelski, a Boulder, Colo., bicyclist who competed in the 2004 Olympics in Athens and is a contender for a spot on this year's U.S. mountain biking team, said that when he arrived in the Chinese capital, the sky was a crystal-clear blue and he thought that concerns about pollution had been overblown. But on the day he was to race, he said, the smog was so thick "you could barely see a few city blocks" from his hotel window.

About 20 minutes into the race, Horgan-Kobelski started having trouble breathing.

"I struggled with it for a while," he said in a phone interview. "You're breathing as hard as you can but you feel like your muscles don't want to work. You're filling your lungs but you don't know what's going in there."

About halfway through the roughly 30-mile race, Horgan-Kobelski said, "my body sort of shut down." He pulled over and vomited.

It wasn't until he got to the athletes' lounge that he learned that he wasn't unique. Only eight of 47 contestants in the men's race finished; the others, including the Chinese riders, also suffered from breathing problems and dropped out.

Now medical teams around the world are trying to figure out what could give their countries' athletes an edge in a polluted atmosphere.