Bromine atoms are even more efficient catalysts; hence brominated CFCs are also regulated.

The term originally referred only to dilution of atmospheric .

This depletion is slight in C4 plants but much greater in C3 plants which form the bulk of terrestrial biomass worldwide.

The resulting value will give the number of carbons as the first numeral, the second numeral gives the number of hydrogen atoms, and the third numeral gives the number of fluorine atoms.

The rest of the unaccounted carbon bonds are occupied by chlorine atoms.

CFCs and HCFCs are usually produced by halogen exchange starting from chlorinated methanes and ethanes.

Illustrative is the synthesis of chlorodifluoromethane from chloroform: The brominated derivatives are generated by free-radical reactions of the chlorofluorocarbons, replacing C-H bonds with C-Br bonds.Depletion in CAM plants vary between the values observed for C3 and C4 plants.In addition, most fossil fuels originate from C3 biological material produced tens to hundreds of millions of years ago.The value of this equation is always a three figure number.An easy example is that of CFC-12, which gives: 90 12=102 -.C4 plants did not become common until about 6 to 8 million years ago, and although CAM photosynthesis is present in modern relatives of the Lepidodendrales of the Carboniferous lowland forests, even if these plants also had CAM photosynthesis they were not a major component of the total biomass.