What you do to save the
ozone layer
There's good and bad ozone, depending on where it is, though
both are chemically identical-a gas formed when three atoms of oxygen, rather
than the normal two, bind together. The ozone found at ground level, a
by-product of car and factory pollution, is one of the more dangerous
components of smog. But in the earth's stratosphere, about 10 to 25 miles above
us, ozone functions as a natural screen against the sun's most damaging
ultraviolet (UV) rays. Unfortunately, the ozone that pollutes our air cannot
reach the stratosphere's ozone layer.
What CFCs do
The stratospheric ozone layer is being destroyed in large part by man-made components called chlorofluorocarbons, or CFCs. These versatile chemicals, in liquid or gaseous form, have helped shape modern society. CFC s are used in coolants in our homes, cars and refrigerators; as foaming agents in foam insulation, mattresses, and food packaging; and as solvents that remove impurities from computer microchips and electronic equipment. The same properties that make CFCs efficient and safe for so many industrial uses also make them destructive for the environment. Their great stability ensures that when they are released into the air (during manufacturing, from leaky cooling systems, or upon disposal) CFCs eventually rise intact into the stratosphere, where radiation breaks them down into component atoms. One of these atoms, chlorine has a devastating effect on ozone. Other compounds called halons, used in some fire extinguishers, are even more destructive of ozone.Scientists predict that by allowing more UV radiation to reach the earth, the depletion of the ozone layer will lead to an increase in the number of cases of skin cancer (especially melanoma) and cataracts. In addition, they postulate that the increased UV radiation may damage crops, kill plankton that serve as a food source for marine life, and even have adverse effects on the human immune system. CFCs may also trap heat in the atmosphere and thus contribute to the global warming trend (greenhouse effect).
For all these reasons, an international agreement in Montreal in 1987 called for phasing out CFC and halon production, and this past May in Helsinki these nations agree to rate the timetable. Recent reports by NASA that the ozone layer is being depleted even more rapidly that was previously projected, and the discovery of vast holes in the layer over Antarctica and the Arctic, have prompted scientists and environmental groups to call for a complete and rapid phase-out of CFCs. But even if we stopped using CFCs tomorrow, the damage to the ozone layer will continue, since those CFCs already released into the air will still be making their way to the stratosphere a decade from now and destroying the ozone for up to a century.
Substitutes have already been found for certain uses
of CFCs. For instance, the EPA banned the use of CFCs as propellants in most,
but not all aerosol sprays in 1978. CFCs can be modified so they do much less
damage to the ozone layer, or so that they break down quickly in the lower
atmosphere. Industries are also seeking ways to recycle the chemicals so that
they aren't released into the air. Dupont, the world's largest manufacturer of
CFCs, last year announced that it would phase out production by the end of the
century.
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