The discovery of the "ozone hole" over Antarctica aroused worldwide concern when it was announced. The first definitive evidence of deterioration in the upper atmosphere's protective layer, it led to the Montreal Protocol mandating phaseouts of ozone-depleting CFCs used in refrigerants and the manufacture of plastic foams, and halons used in fire extinguishers. The U.S. and other industrialized countries have until 2000 to comply; developing nations must do so by 2010.
But the Montreal Protocol provides too little, agreed upon too late. New findings show the ozone shield thinning out and not recovering during summer months as once believed. This thinning allows heavier than normal doses of ultraviolet radiation to pass through the atmosphere and reach the ground. That heightens the risk of skin cancer for people who vacation or engage in extensive outdoor activity. It also threatens damage to agricultural crops and disruption of marine feeding patterns.
The situation is deteriorating. In April, the Environmental Protection Agency said that during the last decade, the size of upper-air ozone diminished by 4.5 percent over the U.S. The EPA said this meant 12 million Americans would develop skin cancer. More than 200,000 could die in the next half-century.