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Ozone is a highly reactive molecule that easily reduces to the more stable oxygen form with the assistance of a catalyst. Cl and Br atoms destroy ozone molecules through a variety of catalytic cycles. In the simplest example of such a cycle, [18] a chlorine atom reacts with an ozone molecule (O
HFOs have an ozone depletion potential of 0.0, compared to the 1.0 of principal CFC-11, and a low GWP which make them environmentally safer alternatives to CFCs, HCFCs and HFCs. [ 63 ] [ 64 ] Hydrofluoroolefins serve as functional replacements for applications where high GWP hydrofluorocarbons were once used.
The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1.0. Chlorodifluoromethane (R-22), for example, has an ODP of 0.05. CFC 11, or R-11 has the maximum potential amongst chlorocarbons because of the ...
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Ozone absorbs both ultraviolet (UV) radiation from the sun and infrared radiation emitted from Earth's surface. [4] Human activity has depleted ozone in the stratopshere and increased its abundance in the troposphere, producing opposing radiative forcing effects. [4] Estimates of the magnitudes of these effects have considerable uncertainty.
Ozone in the troposhere is determined by photochemical production and destruction, dry deposition and cross-tropopause transport of ozone from the stratosphere. [2] In the Arctic troposphere, transport and photochemical reactions involving nitrogen oxides and volatile organic compounds (VOCs) as a result of human emissions also produce ozone resulting in a background mixing ratio of 30 to 50 ...
It was the mid-1970s, three decades after Midgley’s death, before the damage from his two inventions became publicly known. CFCs had punched a hole in the ozone layer over Antarctica; if left ...
Because the concentration of CFCs in atmosphere is very low, the probability of a terminating reaction is exceedingly low, meaning each radical can decompose many thousands of molecules of ozone. Even though the use of CFCs has been banned in many countries, CFCs can stay in the atmosphere for 50 to 500 years.