An active sampler for monitoring polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in air was developed using an automobile air filter set. The performance of the mobile air sampler was evaluated. Recoveries of PCDD/F congeners ranged from 62.3% to 64.5% with sampling volumes of 500-1,800 m³. Air samples were collected between April and June, 2007 in Beijing. The monitoring results of PCDD/F levels by the mobile sampler were comparable to results obtained by a conventional stationary high-volume active sampler. The results suggest this mobile air sampling technology is a promising new strategy for the assessment of air quality in urban areas.