The U.S. Court of Appeals yesterday put the burden on insurance companies to pay the entire cost of damage claims brought by workers exposed to asbestos, even though those insurance policies may have expired by the time the workers became ill and filed lawsuits.

The court ruled in a suit brought by Keene Corp., based in New York, which has been been a target of more than 10,000 damage cases brought by workers who claim they were exposed to asbestos while working in a Keene subsidiary in Pennsylvania from 1948 to 1967. Keene acquired the company in 1968.

Most of the lawsuits were filed after 1979, when workers believed they had confirmed they suffered from asbestos-related diseases, including lung cancer.

At that point, three major insurers claimed that since their policies had expired by the time those cases were filed they should not be held responsible to cover the manufacturer for damages.

Keene argued, and the appeals court agreed, that since the policies were in force at the time of exposure, and while disease may have been developing after exposure, those insurers should be held liable for damages.

Jerold Oshinsky, an attorney for Keene, said yesterday that the appeals court decision greatly increases the amount of insurance money available to both the manufacturers and the workers who claim they are victims of asbestos-related diseases.

The appeals court ruling, written by Senior Judge David L. Bazelon, overturned a lower court ruling, by U.S. District Court Judge June L. Green, which held that only insurers who covered the manufacturer during the time of exposure would be liable for damages.

Bazelon said the manufacturer, when it bought general liability coverage from those insurers, had a right to expect that those policies would protect them from liability for injuries that might not be manifested until years after the policies expired.