Methods Seven sets of centralized HVAC system from five five-star grade hotels in Beijing were selected for sampling monitoring and videotaping in situ from August 2003 to October 2003.

• 方法在2003年8-10月间对北京市5家五星级宾馆的集中空调通风系统进行现场采样、检测和录象。结果5家宾馆的7个系统中,有6个系统积尘量属严重污染,1个系统属中等污染;