Prof. F. Nieman and Prof. Shawn were first to discovered in 1973 that chlorofluorocarbons (CFCs) were depleting the Earth’sozone layer when released into the atmosphere. Once they reach the...

Prof. F. Nieman and Prof. Shawn were first to discovered in 1973 that chlorofluorocarbons (CFCs) were depleting the Earth’sozone layer when released into the atmosphere. Once they reach the stratosphere, Clis released from the CFCs molecules by interaction with UV light. Free Cl atoms areable to react with ozone in a catalytic cycle that converts O3 into the more stable O2.It is estimated that a single Cl atom is able to react with∼100000 O3 molecules.Although CFCs production was banned in 1996, there are still a substantial numberof motor vehicle air conditioners (MVACs) that use CFC-12 (CF2Cl2) as refrigerant.The average CFC-12 emission rate from operating MVACs has been estimated tobe 59.5 mg per hour per vehicle (Zhang et al.Environ. Sci. Technol. Lett.2017).How much chlorine, in kg, is added to the atmosphere in a year due to 100 million MVACs using CFC-12 as refrigerant?