A method coupling trace gas analysis with air sampling was employed to examine relative emission strengths of several regulated halocarbons. A total of 51 air samples were taken in a random manner throughout the Taipei metropolitan area within one hour period. Several background air samples were also collected on the east coast of Taiwan to provide baseline conditions. The concentrations of CFC-11 (CCl3F), CFC-113(CCl2FCClF2), and CCl4 throughout the city were found to be uniform and close to the background levels, suggesting emissions were insignificant. By contrast, the variability in concentrations for CFC-12 (CCl2F2) and CH3CCl3 were large and exhibited area dependence, implying significant usage. (C) 1998 Elsevier Science Ltd. All rights reserved.