DISTRIBUTION AND TREND OF CHLORODIFLUOROMETHANE (HCFC-22) IN THE ATMOSPHERE

Atmospheric concentration of HCFC-22 in the Northern and Southern Hemi spheres over the past 15 years was measured by using an oxygen sensiti zed ECD (electron capture detector). The global concentration increase d by about 5.2 +/- 0.4 pptv (pptv=10(-12) v/v) per year for the period 1980-1988, and about 10.3 +/- 0.2 pptv per year for the period 1988-1 994. The observed result until 1988 was consistent with the mixing rat ios calculated by 2-box model based on the statistical figures of prod uction and emission with 14.0 +/- 1.5 years lifetime. However, the obs erved data suggest that the statistical figures of HCFC-22 emission ha ve been underestimated since 1988.