High frequency monitoring of hydrofluorocarbons (HFCs) and some other halocarbons in the atmosphere has been performed at Hateruma Island (lat. 24.1¿N, long. 123.8¿E), a background site in east Asia. The observed concentrations showed occasional short-term enhancement events over hours to days as well as a clear seasonal variation, being lower in summer than in other seasons. We found that HFC-23 enhancements were closely related to the air transport from China. Using a tagged simulation from three-dimensional transport model and a tracer-ratio technique, the emission rate of HFC-23 from China was estimated to amount to 10 Gg (= 10 000 metric tonnes) per year with an uncertainty of 50%, which could account for two thirds of the total global emission. HFCs emitted from Japan, Korea, and Taiwan were characterized by a predominance of HFC-134a with very little contribution of HFC-23.