Recent global measurements of CHClF2 (F-22) are reported. Originally, GC/MS techniques were used to obtain these data. Since then, significant advances using an O2-doped electron capture detector have been made in the analytical techniques, so that F-22 can be measured by EC/GC methods at ambient concentrations. The atmospheric burden of F-22 calculated from these measurements (average mixing ratio, mid-1979, ~45 pptv) is considerably greater than that expected from the estimates of direct industrial emissions (average mixing ratio, mid-1979, ~30 pptv). This difference is probably due to underestimates of F-22 emissions. |