China's air pollution to keep marathon world record-holder out of Olympics. Is it that bad?

Ethiopian Haile Gebrselassie pulls out of Beijing marathon because of pollution. The marathon world record-holder said yesterday that he was unlikely to compete at the Beijing Olympics because China's air pollution would damage his health. http://ping.fm/Ozifx Is the air that polluted to breathe for anyone, ie, how filthy is the air? http://bit.ly/naTml5