The International Olympic Committee issued a statement yesterday and acknowledged for the first time that air pollution could affect the health and performance of athletes at this summer's Olympics in Beijing. (I wouldn't be surprised if you see more doping cases at this years Olympics to try deal with the conditions) The International Olympic Committee also stated that it would monitor air quality daily during the Games to determine whether to postpone certain outdoor events. Air-quality problems could decrease the potential for world records and peak performances in all sports while creating a possible health risk in outdoor endurance events such as the marathon, triathlon and road cycling, the committee's highest-ranking medical official said. With all these problems, I wonder why Beijing was even selected to host the Olympics, Athletes train for years to reach their peak level and hope to perform well at the Olympics, but now they might not be given the opportunity to perform at their best because of air quality.
You can find out more about this here