Health and environment
Health and environment

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Health and environment

5.4 The ozone hole

Another group of greenhouse gases, the chlorofluorocarbons (CFCs), are double villains because they are also implicated in the destruction of the ozone in the upper atmosphere. CFCs are synthetic gases used in aerosols, as solvents and as coolants in refrigerators. They are also used to make a light insulating material called Styrofoam, from which packaging for hot take-away food containers can be constructed. It has been relatively easy to get international cooperation to ban further production of CFCs and you might be able to hazard a guess as to why this should be so.

Question 28

Why would it be easier to stop the release of CFCs into the atmosphere than to prevent further emissions of carbon dioxide?

Answer

We can find other substances to take over the function of CFCs. We do not depend upon them in the way that we depend upon combustion to release various types of energy.

Production of CFCs should eventually cease altogether, thanks to universal consensus concerning their deleterious effects on the environment. An international agreement aimed at achieving this (known as the Montreal Protocol), was signed by most of the industrial nations in 1987. Unfortunately, CFCs are stable compounds and only decompose slowly, so they will contribute to global warming for some time, especially as each CFC molecule has the same effect as about 201000 molecules of carbon dioxide. As CFCs decay, they release chlorine and it is this gas that leads to the breakdown of the ozone layer. Ozone in the upper atmosphere helps to shield plant and animal life from dangerous ultraviolet (uv) radiation. Since the thinning of the ozone layer was first noticed, there has been an increase in the reported incidence of of skin cancers. There is another part of our bodies that is particularly susceptible to damage from uv radiation.

Question 29

Name the organ that is most easily damaged by sunlight.

Answer

The eye.

So you won't be surprised to learn that the increased incidence in cataracts is attributed to increased exposure to uv radiation. Finally, it should be mentioned that laboratory studies indicate that the effectiveness of the immune system is compromised by uv radiation.

SK220_2

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