Everyone's watching the weather these days, particularly in Beijing. The Chinese government has removed many cars from the roads, suspended construction work and closed factories. But as the Summer Olympics approach, Beijing remains shrouded in a stubborn haze of particulate matter.
Last week, the level was two to three times the standard set by the World Health Organization. The air was better over the weekend, but a haze returned yesterday.
Experts say that unless it is swept away by wind or rain, the dirty air could mean fewer Olympic records, slower times run by many athletes and higher health risks.
Taking cars off the roads and closing factories helps - but what would really do the trick is a good gully-washer or a day of strong winds, experts say.
"A lot is going to depend on weather patterns," said Kenneth W. Rundell, director of respiratory research and director of the Human Physiology Laboratory at Marywood University in Scranton, Pa.
Olympic athletes are taking precautions that include wearing high-tech masks once they arrive in Beijing and using acupuncture to build up lung function and immune systems.
"The air is a serious concern for all the athletes going over there," said Dennis Mitchell, a three-time Olympic medalist coaching two members of the Olympic track and field at the National Training Center in Clermont, Fla.
Damu Cherry, one of Mitchell's athletes who will compete in the 100-meter hurdles, was able to stop taking her asthma medications about three years ago because acupuncture treatments were so effective, Mitchell said.
"You try to find as many natural ways to help as you can," Mitchell said.
High-tech masks, developed in secrecy, are designed so athletes can limit the intake of polluted air once they arrive in Beijing, according to an Olympic spokesman.
"Will we have an edge over other countries that don't wear anything over their mouths? Perhaps. Obviously we want to do all that we can to put our athletes in a position to win medals," Tim Yount, a U.S. Olympic Committee spokesman, wrote in an e-mail.
Health experts are divided over whether Beijing's air - which had two to three times the particulate matter of Los Angeles as of 2004 - can cause lasting damage to the lungs of those visiting.
But most agree that with air so polluted, athletes could feel a difference in their lungs with only one or two days of exposure and that it will make it harder for them to reach peak performance levels.
"I'd wager times and distance events will be well under previous Olympics and that will be proof right there," said Dr. William H.B. Howard, a surgeon who is director of the Arnold Palmer Sports Health Center at Union Memorial Hospital.
Howard said that if the air doesn't clear, many athletes might be off their peak times by 1 or 2 percent, a huge difference considering the fractions of seconds that often separate gold medalists from Olympic also-rans.
"You'll hear more horror stories when these people who are trying to compete go out there and have trouble and say, 'I just couldn't do it,' " Howard said.
Those with asthma will be particularly susceptible to Beijing's dirty air, experts say. About 8 percent of the adult population worldwide has asthma, a rate seen in both the general population and among competitive athletes.
When you exercise, you breathe in oxygen and release carbon dioxide, sending oxygen through the lungs to muscles to make them work, said Dr. Aldo Iacono, a pulmonary and critical care specialist who is medical director of lung transplants at the University of Maryland Medical Center. Polluted air inhibits that process, making it harder to breathe, he said.
"You can't get oxygen to the working muscles, so it would certainly affect their exercise performance," he said.
Exposure to air pollution also is believed to prompt a cardiovascular response that increases the risk of potentially fatal heart attacks, experts say.
A 2004 report published in the Journal of the American Medical Association attributed 3,000 cardiac deaths in the U.S. each year to ozone pollution.
"They're breathing air that can not only make them sick, it can put their lives at risk," said Janice Nolen, a spokeswoman for the American Lung Association.
Exercise requires breathing in 10 to 20 times more air than is required when standing still, so competitive athletes are letting more pollutants into their lungs, said Rundell, a former physiologist with the U.S. Olympic Committee.
This means athletes are more likely to be affected by dirty air as microscopic particles from car exhaust and factories lodge in their lungs. Lungs become inflamed and airways tighten.
"I do think it's going to affect performance. It's going to affect the asthmatics as well as the non-asthmatics," Rundell said.
Researchers who exposed cyclists to polluted air found that it had little effect on their performances when initially exposed for six-minute intervals, he said.