Atmosphere, fluorocarbon concentration

Some of the common anthropogenic chlorinated molecules such as CH3CCL (Methylchloroform) and CHCIF2 (Fluorocarbon-22) are not fully halogenated, and contain C-H bonds which are susceptible to reaction with tropospheric HO radicals. The most abundant of these in its present atmospheric concentration is CHjCCh which is decomposed by reaction (5). 

Rowland F.S. and Molina M.J., Estimated future atmospheric concentrations of CCljc (Fluorocarbon-11) for various hypothetical tropospheric removal rates. J. Phys. Chem. , 80, 2049-2056 (1976). 

When Molina and Rowland made their prediction in 1974, world production of CFCI3 and CF2CI2 was approximately 0.3 and 0.5 Mton respectively fluorocarbon production in the US was growing by 8.7% per year around 1970 [27]. Six years later, and every year since then, the predicted ozone hole was detected over Antarctica, when the chlorine concentration in the same atmospheric layer was approximately 2000 pmol mol [29]. After this dear evidence of the deleterious effects of CFC, in 1987 this class of substance and most bromofluorocarbons were banned from further industrial use in the Montreal Protocol (ratified by the first 29 states in 1989). Because of the decade-long lifetime of stratospheric CFC, their phasing-out can be expected to show an effect no earlier than approximately 2040. 

Eluorocarbons are a class of chemicals widely used in various technologies, including air conditioning, aerosol cans, and fire extinguishers. While the chemicals have proved extremely useful, it was not until the 1970s (when growing concentrations of chlorine were detected in the upper atmosphere) that scientists first reafized that chlorofluorocarbons (CFCs), a type of fluorocarbon, could potentially destroy ozone. 

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