Before the 2008 Beijing Olympics, there were widespread fears about the effects of air pollution on the performance, and even the health, of participating athletes. It is an issue that has followed the summer Olympics around the globe, from the high altitudes of Mexico City in 1968 to the crowded roads of Athens in 2004.
Beijing implemented an extraordinarily varied series of measures to achieve a level of air quality accceptable for athletic competition. Factories were closed – in some cases permanently, traffic levels controlled, and consumption of coal reduced in order to meet targets set by the World Health Organisation and the International Olympic Committee.
via Beijing and London: air quality and the Olympics – Web Exclusive Article – Significance Magazine.