Q. Occasionally, we run across asbestos shingles. We sometimes have to cut the material for a door or window opening. What precautions need to be taken when cutting through this material? What is the best way to dispose of a few shingles? Is this material still available for repairs?

A.Cutting or breaking asbestoscement board or shingles releases asbestos fibers into the air. To remove shingles without breaking, apply pressure near the nail head to expose the head enough to cut it off with side-cutters.

If at all possible, asbestos shingles should be cut with a shingle cutter. Sawing siding panels with an abrasive saw will release large quantities of fibers. The shingles can also be scored with a carbide knife and snapped clean. In either case, a respirator with a HEPA filter should be worn.

There is considerable controversy over whether incidental exposure to chrysotile (white) asbestos, the type used in most residential work, presents any danger. Research in Europe, primarily in the United Kingdom, indicates that mild exposure presents no significant hazard. The blue and brown types used in commercial and industrial applications are different minerals, and seem to constitute a much greater hazard. Extended exposure to any of the mineral fibers is very hazardous.

The requirements for disposal vary from state to state. Some states require that the material be enclosed in a crate or heavy plastic bag, and be buried in a hazardous waste landfill. Other states only require that it be bagged and marked, but buried in the ordinary landfill.

Cement-asbestos board and shingles have not been manufactured in this country for several years. Some shingles have been imported from Canada. Now, imports are prohibited as well. There may still be some in stock at supply yards, but the stock will soon be gone.