The U.S. Court of Appeals here has ruled that cars equipped with antipollution devices that meet only California state clean air standards can be sold nowhere else in the country.

The situation arises because California has been allowed since the original Clean Air Act of 1967 to set its own standards because of the saturation of cars in Southern California. Until 1977, however, the standards set by California were similar enough to federal standards to allow cars sold there to be sold anywhere.

In 1977, however, the state changed its standards so that even though they are still overall as strict as those in the rest of the country, they differ in significant aspects. For example, California allows less nitrogen dioxide and more carbon monoxide to be emitted.

Congress approved the exception for California, and the Environmental Protection Agency let the California standards take effect.

The Ford Motor Co., the Motor Vehicle Manufacturers Association and the Automobile Importers of America challenged the California provisions because they limited the locations where cars can be marketed. Actually, the challengers said, the California standards were better than those anywhere else in the country, the California cars would cost less to make and they would use less gasoline.

The appeals court last Friday upheld the EPA'S decision that it was up to Congress, and not the environmental agency, to decide whether the California cars could be marketed nationwide.

The appellate panel, in a 2-to1 decision, agreed that the California plan may indeed be a "better mousetrap" but said it was not allowed by the Clean Air Act as it was approved by Congress.

U.S. Circuit Chief Judge J. Skelly Wright wrote the court's opinion and was joined by U.S. Circuit Judge Roger Robb.

U.S. Circuit Judge George A. MacKinnon dissented, saying Congress would have been more explicit if it "had intended such a restrictive burden on interstate commerce."