WEATHER LORE

SLIP! SLOP! SLAP!

‘Slip! Slop! Slap!’Slip on a T-shirt, slop on the sun cream and slap on a hat; part of an Australian campaign to increase public awareness of the skin cancer problem.

Australia is said to have the highest rate of skin cancer in the world with two out of three Australians developing some form of skin cancer during their lifetimes.

But why has there been such an increase in skin cancers and why are we so much more concerned about the dangers posed by the sun and the Ultra-Violet radiation it emits?

Ozone is the answer, or more correctly the lack of it! Ozone is a gas containing three oxygen atoms compared to the two of normal atmospheric oxygen, and it has its highest concentrations in the Stratosphere between 20 and 30 km above the surface of the earth.

Ozone is an immensely important constituent of the atmosphere; without ozone it is doubtful if there would be any life on earth. Its importance lies in the fact that it absorbs potentially lethal Ultra-Violet radiation from the sun.

Ultra-Violet radiation is only one part of the electromagnetic spectrum of radiation reaching us from the sun. This solar radiation or insolation also includes visible light and, at longer wavelengths, infra-red. Although U/V radiation has some unharmful effects such as tanning and beneficial ones such as stimulating the production of Vitamin D in people, too much is a real danger to life.

A surfeit of U/V radiation can cause skin cancers, eye disorders and damage to the immune systems of humans, and it can also have a marked negative impact on all the worlds plants, animals and marine life.

So what’s happening to the ozone? Well, gases we humans produce, especially CFC’s (chloroflourocarbons) have been reducing the content of ozone in the Stratosphere, producing the so called ‘hole’ in the ozone layer.

Discovered in the early 80’s above Antarctica, the hole continued to grow throughout the final years of the 20th Century. A similar though smaller hole was found over the Arctic Ocean and even in mid-latitudes like Britain a 3% depletion of ozone per decade has been recognised.

There is some good news, however, which may illustrate that the nations of the world can pull together to combat global atmospheric and environmental problems. Conferences, Agreements, Commitments and Protocols entered into by many countries have reduced CFC emissions significantly and there’s evidence that the size of the ozone hole may have peaked.

The earth’s natural sunblock may be repairing itself; the hole may be self-darning! But, for the moment at any rate, ‘Don’t forget the sunscreen!’ Oh, and returning to the Aussie campaign, ‘wrap on the sunnies!’