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Freon is a CFC  

One chlorine atom can break down 100,000 ozone molecules in the straosphere. When it comes to the hole in the ozone layer, there is good news and bad news. More...

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HEALING THE HOLE IN THE OZONE LAYER
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With the active dialog about global climate change, you may be wondering whatever happened to the hole in the ozone layer. There is good news and bad news.  But first, a brief recap.

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The stratosphere is the part of the earth's atmosphere that extends from the top of the troposphere to about 30 miles above the surface.

After some people died in the 1920's when methyl chloride leaked out of refrigerators, the search for a “safer,” less toxic alternative began. Chlorofluorcarbons (CFCs) were first synthesized in 1928 by a General Motors chemist. By 1935, 8,000,000 refrigerators with Freon-12 (a CFC) had been sold.  Eventually CFCs were widely used in air conditioners, and as cleaning agents, propellants in aerosol cans, etc. 

But in 1974, a couple of scientists from the University of California suggested that man-made organic halogen compounds like CFCs might attack ozone. Ozone is a very reactive type of oxygen formed naturally in the upper atmosphere (called the stratosphere). A blanket of ozone absorbs ultraviolet radiation from the sun, making life on earth possible. If the blanket thins, it could cause problems like skin cancer, cataracts, and unpredictable damage to the food chain. 

Some representatives of the aerosol and halocarbon industries disputed the theory. The Chair of the Board of DuPont called it “a science fiction tale...a load of rubbish...utter nonsense." However, within three years, laboratory measurements and direct scientific observations confirmed the scientists’ hypothesis.  It is estimated that one chlorine atom can break down 100,000 ozone molecules.  

In response, the U.S., Canada, Sweden and Norway proactively banned the use of CFCs in aerosol cans in 1978.  Then in 1985, a shocking report was published in Nature about the discovery of massive ozone hole - three times the size of Australia – over Antarctica.  Within just two years, the international community developed the Montreal Protocol. This global treaty, which went into effect in 1989 and was subsequently tightened, banned CFCs (except for some emergency uses) by the year 2000.  

The Good News.  The information galvanized both scientists and politicians into action. Because there is no significant, naturally occurring source of CFCs, they were able to determine that humans were the source.  International cooperation, coupled with funding and incentives to get developing countries on board, resulted in a complete phase out of CFC use in just ten years.  CFC concentrations in the stratosphere appear to have peaked in 1994, and have since have leveled off. 

The Bad News. CFCs are still in the stratosphere and will continue impacting it for decades to come.  Although levels have begun to stabilize, the hole in the ozone layer has not gone away. Weather systems are complex enough with forces like wind and ocean currents and temperature variations. Throw in carbon dioxide emissions and it gets even more complicated.  Ironically, as the climate warms, the stratosphere actually cools off, which can further deplete ozone layers.  The largest ozone hole recorded so far was measured in September 2006, perhaps due to weird weather in Antarctica. 
We seem to have dodged this bullet because of prompt action by the international community and the ready availability of replacement compounds that were only slightly more expensive than the offending CFCs.  But it looks like the last chapter on the impact of messing with Mother Nature has not been written.

 

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published in the Villager newspapers on February 2, 2007
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