PUNTA ARENAS, Chile — The worst of the ozone hole has pulled back once more to Antarctica this southern spring, leaving behind a shadow of uncertainty for people living at the bottom of the Americas.
How many will develop skin cancer? How many more decades must their children live with dangerous ultraviolet rays? Will the global treaty to save the ozone survive until then?
The people of wind-blown Punta Arenas, like the local evergreens forever bent eastward from westerly gusts, are adjusting to the intense radiation that pours each year through the gap in the ozone layer. At least that's what some say.
"People are better informed. They're buying more sun block and putting it on their children," pharmacist Gerardo Leal said.
"They've gotten used to it," taxi driver Rene Bahamonde assured a visitor. But on a "red alert" day when UV rays could have damaged eyes, his dark glasses sat unused.
And local health chief Dr. Lidia Amarales said many of the 150,000 Punta Arenans took few precautions against a damaging sun as they went about their business on the streets that slope downward to the broad, chill waters of the Strait of Magellan.
The reason is simple: It's cool here. "When it's 30 degrees (86 Fahrenheit) somewhere, people don't go out into the sun. Here, with 13 degrees (55 Fahrenheit), they go outside," Amarales said.
This is a gray, drizzly corner of South America, but clouds are no protection against UV. The temperature rarely exceeds 70 Fahrenheit and "without the heat, they don't 'feel' the radiation," Amarales said. "We need to change habits."
The stratosphere's layer of ozone, a form of oxygen, filtered out almost all the sun's cancer-causing ultraviolet-B rays for millennia. But in the 1970s, scientists warned that artificial chemicals such as chlorofluorocarbons (CFCs), used in aerosol sprays and refrigerants, were destroying ozone through chain reactions high in the skies. By the 1980s, satellite images showed that an "ozone hole" had formed over Antarctica.
Air currents and intense cold in the polar region, plus chlorine from CFCs, created a vast expanse of ozone-thin atmosphere that briefly reached the tip of South America each spring. Ozone here was found in October 1992 to have thinned to 147 Dobson units, less than half the normal 333. Ultraviolet radiation, in its most damaging wavelengths, multiplied many times.
