From chlorofluorocarbons

The chlorine atoms that catalyze the decomposition of ozone come from chlorofluorocarbons (CFCs) used in many refrigerators and air conditioners. A major culprit is CF2CI2, Freon, which forms Cl atoms when exposed to ultraviolet radiation at 200 nm ... 

Ko, M. K. W., N. D. Sze, and G. Molnar, Global Warming from Chlorofluorocarbons and Their Alternatives Time Scales of Chemistry and Climate, Atmos. Environ., 27A, 581-587 (1993). 

These results suggest that the transition from chlorofluorocarbon-containing to chlorofluorocarbon-free metered-dose inhalers is possible without concerns about safety and efficacy. 

Changes to manufacturing processes of propellant-based metered-dose inhalers (pMDIs) due to the transition to hydrofluoroalkane- (HFA-) based formu lations from chlorofluorocarbon- (CFC-) based systems are under way. These changes are proceeding concurrently with reformulation efforts of the pMDI systems themselves. In some cases, this may result in changes to the formulation [1],... 

Catalysts in the Earth s atmosphere are causing troubles. They are causing the ozone layer to break down. Ozone protects the Earth from harmful ultraviolet rays from the Sun. Chlorine is a catalyst in the upper atmosphere. The chlorine comes from chlorofluorocarbons, or CFCs, released into the atmosphere. Chlorine allows ozone to break down into oxygen. The chlorine remains and keeps destroying ozone. This has caused a hole in the ozone layer. Governments around the world have banned the production of CFCs. This hole in the ozone now appears to be shrinking. We must continue to protect the ozone layer by reducing pollution around the world. Some scientists believe the ozone layer could return to normal levels by 2075. 

Kalcevic, V. McGahan, J.F. Process for Treating Spent Catalyst Including Antimony Halides from Chlorofluorocarbon Production US Patent 4,751,063, Jun. 14, 1988. 

Because nearly all of the chlorine and fluorine released from chlorofluorocarbons resides as HC1 and HF in the stratosphere near 50 km, observations of those two gases in this region provide an important verification of their attribution to CFC sources. Global data by Russell et al. (1996) display abundances and trends in both HC1 and HF near 50 km that are quantitatively consistent with observations of the chlorofluorocarbons at ground level these observations therefore confirm that CFCs are the key sources for stratospheric chlorine and fluorine. Such observations also suggest that the abundance of reactive chlorine reached its maximum in the late 1990s, while fluorine... 

For the last two decades, attention has been focused on redressing the ozone depletion in the earth s protective layer. It is believed that chlorine radicals dissociated from chlorofluorocarbons (CFCs), upon irradiation of sun s UV in the stratosphere, promotes the ozone depletion. Hence, in addition to development of CFC alternatives there is an urgent need for the safe disposal of CFCs. Several processes such as pyrolysis, incineration, photocatalysis, oxidative destruction over metal oxide or zeolite catalysts and destruction at very high temperatures ( by plasma technique ) are reported in the literature for the disposal of CFCs[ 1-5]. But all these processes yield harmful products like CO, HF/F2 etc. Catalytic conversion of chlorinated organics in presence of hydrogen seems to be a better technique as it yields either hydrofluorocarbons(HFCs) or hydrochlorofluorocarbons(HCFCs) whose ozone depletion potential is either zero or very low and yet most of these products act as CFC alternatives. 

The plume velocity is the velocity with which an aerosol is released from an MDI. Generally, the plume velocity from hydrofluoroalkane (HFA) holding MDIs is much lower than that from chlorofluorocarbon (CFG) holding MDIs, but this may depend on the presence of a co-solvent... 

Chemistry in the Environment Chlorine in Chlorofluorocar-bons in Chapter 6 explained that chlorine atoms from chlorofluorocarbons deplete the ozone layer, which normally protects life on Earth from harmful ultraviolet light. Through research, chemists have discovered the reactions by which this depletion occurs. 

Active chlorine originally from chlorofluorocarbons (CFCs) is sequestered in stratospheric clouds during the dark winter above the South Pole and then released during the Antarctic spring (September and October), destroying protective stratospheric ozone and resulting in the Antarctic ozone hole. 

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