by Wm. Robert Johnston
last updated 26 December 2002
Description: The lines show a twelve-month moving average of measured concentrations of CFC-11 (blue line) and CFC-12 (red line) at the surface. The data shown is the average of measurements from Barrow, Alaska, and Mauna Loa, Hawaii (missing values were extrapolated).
© 2001, 2002 by Wm. Robert Johnston.
Last modified 26 December 2002.
Return to Home. Return to Environmental Topics. Return to Some scientific data on the ozone issue.