Some plaster walls contain asbestos. Asbestos was commonly used in the building industry starting in the 1940s, and it was banned for use in paint and patching compounds in 1977. Asbestos is most commonly found in insulation.
Asbestos is a fiber that presents a health hazard if it is inhaled, so the best thing to do is leave any asbestos containing materials alone, according to the Consumer Product Safety Commission. Asbestos that is disturbed by sawing, sanding or scraping becomes airborne and can be inhaled. When there is asbestos in a home, all repairs, including asbestos removal, must be completed by professionals who are specifically trained in handling asbestos, such as an asbestos abatement contractor.