How Do You Patch a Hole in the Sky That Could Be as Big as Alaska?

Think for a moment about the world's 1 billion refrigerators and its hundreds of millions of air conditioners. Picture mountains of foam insulation, seat cushions, furniture stuffing and carpet padding. Imagine streams of cleaning fluids, rivers of industrial solvents, wafting clouds of aerosol spray.

Ridding the planet of the millions of tons of ozone-depleting chemicals contained in that vision is not just a big job; it may be the biggest job the nations of the world have ever taken on. In the 60 years since Du Pont began marketing the miracle refrigerant it called Freon, chlorofluorocarbons have worked their way deep into the machinery of what much of the world thinks of as modern life -- air-conditioned homes and offices, climate-controlled shopping malls, refrigerated grocery stores, squeaky-clean computer chips. Extricating the planet from the chemical burden of that high-tech life-style -- for both those who enjoy it and those who aspire to it -- will require not just technical ingenuity but extraordinary diplomatic skill.

The technical challenge is relatively straightforward. The goal is to find substances and processes that can replace CFC-based systems without doing further harm to the stratosphere -- an endeavor that is well under way. In fact, it may turn out to be easier than anyone expected. Except for medical aerosols, some fire-fighting equipment and certain metal-cleaning applications, there are now effective substitutes for virtually every ozone- depleting chemical. Some cost quite a bit more, and others pose different, if less severe, environmental problems. But in a surprising number of cases, the new processes are actually cheaper and better than the old.

Replacing CFCs in newly built equipment, however, is only half the job. Virtually every existing refrigerator and air conditioner is a CFC reservoir. The chemicals are not a problem as long as they continue to circulate within an appliance. But if the machine is carelessly drained, junked or damaged, the CFCs can escape to attack the ozone. The real task for those countries that invested heavily in CFCs in the past is to develop systems for recovering and recycling the chemicals they have already used.

The diplomatic challenge is trickier. For the U.S., Europe and other industrialized regions to do right by the stratosphere is one thing. They bear direct responsibility for most of the damage that has been done, and they can best afford the costs attached to switching technologies. But what about the countries of the Second and Third Worlds? Many of them are just beginning to enjoy the comforts of CFC technology, and they cannot easily pay for a changeover.