LONDON (Reuters) - Bad air could cause major problems for Olympic athletes who will have to deal with Beijing's pollution and strict anti-doping regulations surrounding asthma medication in August.
Olympic teams across the world are rushing to screen their athletes to determine who has exercise-induced asthma, which can be triggered by smog and hurt performance. Many competitors do not even know they have the condition.
"What we are trying to do is diagnose who has asthma and get them on the right medication," said John Woodside, a physiologist with the English Institute of Sport which is coordinating the testing of Britain's Olympic athletes.
"There has been a special interest in these Olympics because of the pollution factor."
Beijing is one of the most polluted cities in the world and despite a 120-billion-yuan ($17.3-billion) clean-up over the last decade air quality remains a big concern.
Officials have pledged to cut the number of cars on the road during the August 8-24 Games but some athletes are still worried, including twice Olympic champion Haile Gebrselassie, an asthma sufferer who feared running the marathon would damage his health.
The Ethiopian has pulled out of the Olympic marathon, though he hopes to run in the 10,000 meters in Beijing.
Experts believe there is good reason to worry. Tak Lee, an allergy and respiratory medicine researcher at King's College London, said bad air combined with exercise could trigger a debilitating asthma attack.
The condition occurs when people inhale particles from the air during exercise, inflaming the lungs and making it harder to breathe. Some can run through it while others may get wheezy and have to stop.
The problem in Beijing is that all the vehicle emissions, construction sites and factories pumping pollutants into the air when combined with hot, sticky conditions might make it tough for athletes to catch their breath, he said.
"It is a concern," Lee said in a telephone interview. "An attack of exercise-induced asthma can be quite severe."
Karen Holzer, part of the Australian team's medical staff, said the Australian Olympic Committee had increased asthma testing for these Games.
She estimates exercise-induced asthma could affect an athlete's performance by up to 30 percent, underscoring the need to identify and treat people with the condition.
"If they get a moderate increase in the asthma, it may mean they have to pull out of the event," she said.
Once doctors diagnosed an athlete with exercise-induced asthma, getting the waiver for using medication from the International Olympic Committee (IOC) was pretty straightforward, said Woodside.
The problem, however, is that some standard treatments break anti-doping regulations, requiring athletes to think about more than just their training. Many sporting governing bodies have reminded athletes to make sure they know the rules.
Athletes need to ensure they have a valid therapeutic use exemption form so they can take medication.
So-called beta-2 agonists are banned as asthma medication unless athletes have a therapeutic use exemption allowing them to take formoterol, salbutamol, salmeterol and terbutaline when inhaled, according to the World Anti-Doping Agency (WADA).
These treatments work by copying certain effects of naturally-produced chemicals -- adrenaline and noradrenaline -- to open up the airways so that more air reaches the lungs.
"Because some of the medication is on the banned substance list the IOC must be sure that only asthmatic athletes are using asthma medication," said Ken Van Someren, lead physiologist at the English Institute of Sport.
"Although it should be stressed that therapeutic doses of asthma medication will not have any performance-enhancing effect."
The test involves measuring lung function before exercise and then either after 10 minutes of hard exercise or 10 minutes after an athlete takes asthma medication.
A drop of 10 percent or more in lung function was considered a positive test and a signal the athlete needed to see a doctor to get on medication, he said.
At the Los Angeles Olympics in 1984, 1.7 percent of all athletes who competed sought and were granted exemptions to use asthma medication, according to Joseph Cummiskey, a respiratory physician and member of the IOC.
This figure has steadily risen since then and in the 2004 Athens Games 7.4 percent of the athletes were given exemptions, though some were rejected, he said.
Editing by Clare Fallon