Ozone is the poisonous gas we can't live without.
Oxygen that we breathe is made of two oxygen atoms linked together. Ozone is another natural form of oxygen in which three atoms are bonded together. It's one of the main Ingredients in smog, the fog that hangs over cities plagued with air pollution. Ozone also forms around some kinds of electric equipment, like motors and air purifiers. Breathe much of it, and you could have some problems.
Ozone also forms a layer high in the stratosphere called the ozone layer. This layer actually protects life on Earth by absorbing harmful ultraviolet rays from the sun. These rays can cause some kinds of skin can-cer as well as destroy the photosynthetic organisms in the ocean that produce the oxygen we breathe.
However there is a problem. Every spring, the ozone layer develops a hole above Antarctica. It's a good thing there aren't too many people there! Scientists have linked this hole to a class of chemicals that we once used for things like air conditioning and dry cleaning of clothes.
The main culprit was sold for many years as Freon, which chemists called dichlorodifluoromethane (CCI,F,). It was developed in 1930 by Thomas Midgley Jr. and Charles Kettering of General Motors. People used it in refrigerators, air conditioners, dry cleaning solvents, aerosols, and some kinds of foam. Freon and other related chemicals called chlorofluorocarbons (CFCs) are odorless, tasteless, nonflammable, and noncorrosive. They are also not poisonous In small amounts.
In the 1950s, scientists studying the atmosphere discovered the ozone layer and Its shielding effect. In the early 1970s, chemists found that ozone breaks down in the presence of CFCs. They predicted that atmospheric CFCs could dangerously deplete the ozone layer.
It takes several things for this to happen. First you need clouds. In the spring, clouds of ice crystals form In the very high cold air of the stratosphere over Antarctica. These ice crystals speed up certain chemical reactions. To deplete the ozone, you also need CFCs. These chemicals contain chlorine, along with other elements. Sunlight is the third ingredient. If you remember, Antarctic winters see no sun. Not until springtime does the sun reach these areas of the world. When it does, energy in sunlight can break a chlorine atom off a CFC molecule. This chlorine atom reacts with ozone molecules on the surface of cloud Ice crystals to break them down into just plain old oxygen. One single chlorine atom can react over and over again. Oftven a little CFC can do a lot of damage.
These laboratory findings, seemingly supported by atmospheric observations, propelled the global community into action. The United States, along with several other nations, banned CFC production in 1978 In what was called The ozone hole over Antarctica, as seen on 9/6/2000 the Montreal Protocol. As satellite evidence of ozone depletion continued to mount, other countries put bans on producing, selling, and buying CFCs in 1987 and 1993. The laws required that they be replaced with other chemicals. but these chemicals didn't work as well as Freon.
So what happened? Is the ozone hole getting smaller? Were scientists right about the link between Freon and the ozone hole? Has banning CFCs really made a difference?
Well, we're not quite sure. Scientists have been watching the ozone hole for several decades now. It has stayed about the same size, but that size Is quite variable. In 2003, the hole never seemed to develop at all, perhaps because it was too warm. It may take a long time, maybe another 20 Of 30 years or more for CFCs to disappear from the atmosphere. Only then will we be able to tell if our efforts were actually effective in saving the ozone layer.
It's possible there are things about the ozone layer that we just don't understand yet. Time will tell whether this was good and wise dominion or just scientists using an incomplete scientific model, Can man's activities really affect the earth and its systems in such a big way? Should we take immediate action to fix what we think are problems with the Earth's systems? Do we understand Earth's systems well enough to make decisions about these things without understanding very long-term effects, such as solar cycles? These are questions that we must answer before we address what many people believe is the coming catastrophe of climate change.