Saving the ozone layer

In the case of the halons, replacements are also being phased in. For example, halon 1301 (bromotrifluoromethane, CF3Br), widely used as a fire-extinguishing agent to protect sensitive electronic equipment, is being replaced by HFC-227 (CF3CHFCF3), which contains no chlorine or bromine. 

It is sobering to remember that despite the recent success in limiting production of CFCs, these stable substances have a long residence time in the atmosphere, between 40 and 150 years. This means their effects on the stratospheric 03 will continue for some time after the bans on their production. Current estimates suggest that the policies in place should see a decline in the stratospheric bromine and chlorine concentrations over the next 50 years, paralleled by a rise in ozone concentrations. 

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