Q: We have just learned that we have asbestos shingles on our house. Does this pose a health risk? Should we replace them, or can we cover them with siding?

A: Asbestos may be present in many locations throughout your home. However, that does not necessarily mean that it poses a hazard to your health.Many exterior surfaces, such as walls, siding and panels, shingles, roofing felts, and even window putty may contain asbestos. If these materials are left in place and are undamaged, they do not constitute a hazard. If they are damaged or are to be cut, drilled, sanded or removed, however, asbestos fibers may be released, in which case protection is warranted.

The most familiar source of asbestos is found in loose fill, blown-in and batt insulation. Again, if the insulation is left in place, undisturbed, it does not pose a health hazard. If anything disturbs this material, however, such as remodeling or demolition, the asbestos fibers will be released.

Occasionally, old sheet vinyl, vinyl tile or tile adhesive has been found to contain asbestos. When remodeling, it is best to cover the old flooring, if possible. Never grind down or sand the floor surface or adhesive residue.

Additionally, interior walls of older homes may contain asbestos in the construction materials. Left undisturbed, these do not pose a threat. It also was used (prior to 1978) to texture walls and ceilings. If the surface produced a powder or dust simply by hand pressure or as a result of water damage, it would be prudent to consult a professional to advise you as to what actions should be taken.

There are many other areas in and around the home that might also contain asbestos. For example, older model wood-burning stoves, pipe wrapping, insulation blankets on furnaces and boilers may contain asbestos. For the most part, if they are left intact, they pose no health risk.

For additional information, you may wish to obtain the brochure "Asbestos in the Home" published by the Environmental Protection Agency.