McDonald's has decided to stop using chlorofluorocarbons in its fast-food packaging as a gesture toward protecting ozone in the upper atmosphere, the company announced yesterday.

The restaurant chain said it had concluded that "there are reasonable alternatives to possibly harmful CFCs available which will not affect our ability to serve our customers products which are hot and fresh."

Chlorofluorocarbons (CFCs) are used to produce plastic foam products, such as the lidded containers that McDonald's uses to package its sandwiches. Far more of the chemicals are used as refrigerants and in aerosol products.

Scientists have warned for more than a decade that CFCs are destroying the ozone layer that shields Earth from dangerous ultraviolet radiation, which can cause skin cancer. The warnings have become more urgent amid recent evidence that the ozone is thinning measurably over Antarctica.

The McDonald's decision was prompted in part by some gentle nudging from Sen. Robert T. Stafford (R-Vt.), who urged the company several months ago to consider alternatives to CFCs.

Although foam sandwich trays represent a small fraction of international CFC use, they have become symbolic of what critics consider "frivolous" uses of the chemical at the expense of the atmosphere.

Stafford said yesterday that he was "delighted" at the decision. "From now on, McDonald's gets all of my fast-food business," he said.

McDonald's spokesman Lana Ehrsam said the company will continue to use foam packaging, but the products will be manufactured without the use of CFCs. The transition will take about 18 months, she said.

"When we started hearing more about the whole ozone scenario, we started a complete review of our packaging program," she said. "We found an alternative that we feel will work."