House-Senate conferees yesterday hammered out an ambitious package to restore the stratospheric ozone sun screen vital to life on Earth by eliminating the chemicals most destructive to ozone early next decade and their substitutes by the year 2030.

The package, marking the conferees' first agreement on clean air legislation, would commit the United States to a phaseout of the most corrosive substances -- including chlorofluorocarbons (CFCs) -- on a faster timetable than the one included in a protocol approved by the world's industrialized nations in London last month.

It also goes further than the accord by proposing to freeze the production of less corrosive substitutes, called HCFCs, by 2015 and eliminate them 15 years later.

Despite opposition from the Bush administration, the conference agreement melds measures passed by both houses with stronger prescriptions than the international treaty. The compromise is expected to be approved by both chambers.

In setting the deadlines, the conferees intensified pressure on a U.S. consumer industry already facing a comprehensive retooling. CFCs are used widely as a coolant in refrigeration and air conditioning, as a solvent to clean electronics and as the agent used to blow and shape foam products.

Unlike most pollutants, CFCs do not break down in the lower atmosphere. Instead, they waft into the stratosphere about 10 miles above the ground where, bombarded by solar rays, they break up. They release chlorine there that eats up the ozone layer, which blankets the Earth and screens out ultraviolet rays harmful to human health and plant life.

With plans to invest $10 billion over the next decade in less corrosive substitutes, industry sought less stringent deadlines for eliminating them. "We want a reasonable time frame," Kevin Fay, chief lobbyist for the CFC industry, said yesterday.

Environmentalists argued that, without specific deadlines, industry cannot be depended on to stop production of the HCFC substitutes that could become popular worldwide.

The substitutes are called HCFCs because they include hydrogen molecules that force the chemical to break up lower in the atmosphere, farther away from the ozone layer. Scientists say HCFCs are 95 percent less damaging to the ozone than CFCs, but they believe continued HCFC use will prevent full repair of the ozone layer.

Industrialized nations agreed in 1987 to halve their CFC use by the turn of the century. But the accord quickly became outdated by later discoveries that the ozone layer over Antarctica had thinned to as little as half its earlier concentrations and that the protective shield over North America also had diminished.

The treaty was strengthened last month to eliminate CFCs by the year 2000. Methyl chloroform, the most popular U.S. industrial solvent responsible for 16 percent of the chlorine in the stratosphere, would be phased out by 2005.

Conferees set a deadline of 2002 for elimination of methyl chloroform unless there are no substitutes for essential uses. While the final date for phaseout of CFCs remains the same, the annual incremental reductions would be larger.

According to the agreement, HCFCs would be prohibited in 2015 except to service or maintain refrigeration and air-conditioning equipment, which makes up most of the $135 billion in existing devices dependent on CFCs.

"It will go a long way toward dealing with a frightening, cataclysmic threat to our planet," Rep. Henry A. Waxman (D-Calif.), a conferee, said of the agreement.