Ozone levels after CFC ban

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Animated models of the projected polar atmospheric ozone levels from 1974 to 2065, after CFCs (chlorofluorocarbons) were banned. Ozone levels range from high (red) to zero (dark blue) here, and vary seasonally, being most depleted in the spring in each hemisphere. Use of CFCs was banned by the Montreal Protocol in 1989, after work by Frank Sherwood Rowland and Mario Molina showed that they would be carried to the ozone layer and be broken down by solar UV radiation, beginning a process that would destroy ozone. The ozone layer in the stratosphere absorbs much of the harmful UV radiation from the Sun. Measurements showed that there were growing ozone holes, regions of low ozone concentration, over both poles, being particularly strong over Antarctica. Since the ban came into effect the holes have stopped growing, and there is some evidence of repair, although CFCs can last around 100 years in the atmosphere. For the same model showing the projections if CFCs hadn't been banned, see clip K001 3279.

SVS/GSFC/NASA / Science Source

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