Halocarbons ozone reaction with products

The halocarbons, which are not destroyed in the troposphere by reactions with hydroxyl, pass into the stratosphere where they are photo-dissociated to liberate chlorine atoms which attack ozone. Only one of them is of natural origin, methyl chloride CH3CI, but there are also several industrial products, especially carbon tetrachloride, CC14, trichlorofluo-romethane, CFC13, and dichlorodifluoromethane. Methyl chloride (Table III) has a natural marine origin (for details, see ref. 12), but it is certainly present also in the smoke produced when polyvinyl and other products containing chlorine are burnt. In addition, it is produced naturally not only in forest fires, but also in tropical agriculture based on the cultivation... 

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