During the years 1974--1979 the CC13F concentration in the Northern Hemisphere stratosphere increased by a factor of 2. The annual rates of increase were directly related to annual rates of emissions at the surface of the earth. The production data for fluorocarbons, published by the Chemical Manufacturers Association, show a decline in the yearly rate of emission of CC13F during the last decade. The yearly percent increase in the mean stratospheric concentration in the Northern Hemisphere has shown a similar decline. Data for CC14, CCq2F2 and SF6 also show a slowing in the annual rate of increase in the stratospheric mean concentration. The calculated globally averaged concentration of N2O in the Northern Hemsphere remained constant at 249¿7 n1/1 during the years 1976--1979.