Saturday, March 31, 2012

Here Comes the Sun: UV in the Atacama

Throughout the Southern Hemisphere, exposure to ultraviolet radiation, due partially to the ozone hole over the southern oceans, is a major concern. Australia, for instance, has one of the world’s highest skin cancer rates, and an Australian friend in Santiago recently told me that schoolchildren in his country cannot go out to play without a legionnaire-style baseball cap that covers the neck and ears as well as the face.

It’s an issue that concerns me, of course, ever since I had surgery to remove a melanoma about 18 months ago. The ozone hole over Argentine and Chilean Patagonia has long been notorious for its high UV index, but Chile’s Atacama desert is also a dangerous place for those of us with fair skin. At present, I’m in the city of Antofagasta, just south of the Tropic of Capricorn, and, as I head north, the sun’s rays are far more direct and, at high altitudes, the risk is even greater.
In that context, I recall an incident nearly 30 years ago, when I was doing M.A. thesis research in the village of Parinacota (pictured above), at an altitude of 4,392 meters (14,409 feet), in Parque Nacional Lauca. At roughly 18° 10’ South latitude, the sun was powerful and, though I didn’t always wear a cap, I was not reckless about exposure to the sun. Two Australian visitors were far less cautious than I was.

At that time, during the Pinochet dictatorship, foreign tourists were few, but the Aussies arrived one afternoon on the bus from the seaside city of Arica. The only place to stay was Conaf’s refugio, a sprawling structure originally built for a high Andean genetics research project by the University of Texas, if I recall correctly. It had two large dorms with reasonably comfortable bunks and, most of the time, I had one of those dorms to myself. The park rangers slept in the other one and, on this night, I shared mine with the two visitors.

At that altitude, it froze almost every night, even in summer (when it sometimes even snowed, as depicted above), but the next morning was gloriously warm and sunny. The two Aussies took that as an invitation to sunbathe and, before long, they seriously regretted it. That afternoon, they were literally scorched red as lobsters and, on top of that, they suffered a severe attack of soroche (altitude sickness). There were no buses that day but, fortunately, they managed to get a lift back down to sea level. Whether they learned a lesson from their experience, I have no idea.
All that came to mind yesterday when, in the old nitrate port of Taltal about three hours south of Antofagasta, I saw the most detailed public warning about solar exposure that I’ve ever seen, in Chile or elsewhere. In fact, it’s a chart that suggests, according to skin type and the prevailing UV index, what constitutes a “safe” exposure to the sun, and what level of protection is necessary.

Whether the chart in question has any scientific accuracy, I have no idea. But if it raises awareness of solar exposure among the population of Taltal – which also gets plenty of reflected rays off the Pacific Ocean – it should be for the better.

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