Ozone loss can result in lasting damage

"I WOULD take it as a warning," states Prof Howard Sidebottom, a UCD expert in ozone depletion chemistry. "There was a longstanding assumption that man wasn't capable of messing up what God made. But lie is."

The continuing loss of ozone in the Earth's upper atmosphere, caused by human pollutants, provides compelling evidence, if evidence was needed, that we could bring about lasting damage to the Earth's systems.

The latest European research, released last month measured a loss of up to 40 per cent of ozone over the northern hemisphere. Similar losses were experienced during the last Antarctic spring. Ozone depletion there was the worst ever in 1995 with the ozone "hole" covering 10 million sq km and lasting for 77 days.

Upper atmosphere ozone is important to human health because it helps shield us from the sun's ultraviolet (UV) radiation, the part of the light spectrum that makes us tan.

Various EU measuring stations, including our Met Eireann centres in Valentia, Mace Head and Malin Head watch for changes in the amount of UV reaching the Earth's surface.

The new European data showed that UV levels "continued to increase at rates close to about 2 per cent per year" for certain iv wavelengths. Too much UV causes sunburn, increasing the risk of various skin cancers. It can also cause eye cataracts.

Even so, the predicted increase in future skin cancers has less to do with ozone depletion than with our collective determination to get a tan. "The biggest problem with UV is that it is thought good to look brown," Prof Sidebottom says, adding that the danger is not in the ozone loss but in this behaviour.

The current loss, he says, would equate to the increased UV exposure brought about by a move from Dublin to Cork. "That to a human is nothing. It is a problem that is easy to solve."

Much more important, he says, is how increased UV will effect the lower organisms in the oceans around Antarctica which represent the foundation of the food chain there. Damage this and species right up the chain could be at risk.

Humans can break the suntanning habit, keep under cover or use UV blocking creams and overcome the health risks, but the marine ecosystems are trapped under the thinning southern hemisphere ozone layer. What long term impact this might have remains unknown, Prof Sidebottom said.

Mr Gerry Murphy, chief scientist at Met Eireann's Valentia Observatory, oversees UV measurements there and confirms the ozone layer above us continues to thin. The loss, he says, "is not dramatic enough for people to get overly alarmed", but it is still a matter of concern and a reason to continue ozone and UV measurements.

Prof Sidebottom also warns that things will get worse before they get better despite the 1987 Montreal Protocol, which agreed a 50 per cent reduction by the year 2000 in the use of the chlorinebased chemicals which destroy ozone.

Serious depletion will continue to 2020 or 2030, level off and then start to reverse, with a return to previous ozone levels by 2100. Prof Sidebottom predicts this on the basis of the protocol. The lesson to learn from this, he says, is that we can potentially harm ourselves by damaging the environment.