BEIJING -- As Beijing prepares to host the XXIX Olympiad next month, the capital's filthy air is the subject of global scrutiny. Wary of Beijing's pollution, British marathoner Paula Radcliffe said she might wear a respiratory mask before she competes. Ethiopia's Haile Gebreselassie will skip the marathon but run the 10,000-meter race. Dozens of other athletes will train in Japan and Korea until the Aug. 8 opening ceremonies. But Beijing is determined -- some say defiant -- that its skies will be blue and its games green.