The earth's ozone layer is eroding despite the enviro-conscious efforts of industries and consumers to cut back on ozone-eating chemicals, the Geneva-based World Meteorological Organization reports. But is the sky falling? "The worst is still six or seven years ahead of us," Rumen Bojkov, special adviser to the agency on ozone issues, told reporters. On the other hand, he said, the ozone level could recover within a half-century. The report, the work of 226 scientists around the globe, explains that international efforts to reduce the use of chlorofluorocarbons, or CFCs, have made a dent but take a few years to clear the air.