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The layers of earth’s atmosphere as seen from space. Photo: NASA.

The story of the ozone hole illustrates how a successful combination of science and political action can lead to policy that helps solve an environmental problem. The problem was a hole in the ozone layer over the Antarctic, and the policy was to ban the manufacture of chlorofluorocarbons (CFCs).

CFCs were created by a chemist in 1928, and were first produced commercially in the 1930s by DuPont under the brand name Freon. They were used as propellants in aerosol sprays and as an ingredient in refrigerants and air conditioners. The manufacture and use of CFCs increased until the late 1980s.

During the time that the manufacture and use of CFCs were increasing, scientists were studying the effects of CFCs on the environment. Studies indicated that the most important effect was on the ozone in the earth’s upper atmosphere (stratosphere). Ozone occurs naturally in the earth’s upper atmosphere where it plays a critical role in protecting us from harmful ultraviolet (UV) radiation from the sun. Too much UV light can cause cataracts, potentially fatal skin cancers, and damage plant life. Ozone in the lower atmosphere is the result of pollution, causing smog.

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Ozone layers over Antarctica in 1979 (left) and 2008. Purple = less ozone. Photo: NASA.

Scientists started measuring concentrations of ozone over the Antarctic in 1956; satellite measurements started in the early 1970’s. In 1974 two scientists, M. J. Molina and R. S. Rowland, published the results of a laboratory study that demonstrated that CFCs break down in the presence of UV light, releasing chlorine which reacts with ozone. One CFC molecule can destroy 100,000 ozone molecules. As of the mid-1970’s, we knew that CFCs could destroy ozone, but it wasn’t yet known if enough CFCs were getting into the atmosphere to have a significant effect. Those who used the CFCs (pretty much all of us) didn’t think that CFCs could really have an impact on the atmosphere because the earth is huge, after all.

That changed in May of 1985 when the British Antarctic Survey published a paper explaining their discovery of a hole in the ozone layer over the Antarctic that had not been there since measurements started in1956. The discovery of the ozone hole – which allowed damaging UV light to penetrate the earth’s atmosphere – led to the Montreal Protocol in 1987, an international agreement calling for the phasing out of CFCs in consumer products, overriding push back from industry and lawmakers who did not believe the science.

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Depictions of low ozone coinciding with high chlorine. Photo: NASA, 2011.

Since then, the ozone hole seems to be stabilizing – even shrinking, according to NASA – but scientists say it will be 40 to 60 years before CFCs have worked their way out of the atmosphere. The moral of this story is that the chemicals that we produce for use in everyday products can have a negative impact on the atmosphere, and that even when we act to correct things, it takes decades for that impact to go away.

For more information visit NASA.

[Cover photo: Crescent moon in earth’s atmosphere; NASA.]

About the author

Ben Hipple

Ben Hipple lives in McCall, where he enjoys the outdoors by hiking, running and skiing on local public lands. He also enjoys observing the night skies from the his porch. Ben discovered that for the price of a set of skis and boots, you can buy a good telescope, and the best telescope is one you can easily set up and use.

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