The heat and humidity in the Beijing region will present a formidable challenge to all the Olympians, according to a group of researchers, who added that the poor quality of air can also affect all athletes, especially those with asthma.
Experts believe that owing to the poor air quality, exposure to air pollutants might trigger symptoms of asthma in patients.
"With exposure to an environment that has poor quality, air pollutants may trigger symptoms of asthma in a dose-dependent manner," said Donald McKenzie and Louis-Philippe Boulet.
"With the high minute ventilation [amount of air breathed in one minute] seen during exercise, the effects of exposure to these pollutants are more noticeable in athletes than in non-athletes and likely more evident in people with asthma than in those without asthma," they added.
Physical activity and regular exercise can improve the control of asthma but frequent and intense exercise by highly trained athletes could itself contribute to the development of asthma.
Long-term endurance training may influence the structure and function of airways in the lungs and make them hyperresponsive, contributing to the development of asthma.
China has implemented strategies in the Beijing region to improve air quality during the Olympic Games.
"However, a significant percentage of the pollution (about 35pct) at the Olympic Stadium can be attributed to sources outside Beijing. Controlling only local sources of pollution may not be sufficient to achieve the air quality goal set for the Beijing games," they said.
McKenzie and Boulet suggest that athletes with asthma need an individualized management plan that needs to comply with the anti-doping regulations of the International Olympic Committee and the World Anti-Doping Agency.
The review article appears Canadian Medical Association Journal.