Asbestos exposures in Massachusetts public schools.

A Massachusetts legislative commission was established to investigate the potential health hazards associated with the use of sprayed-on asbestos in public school buildings. All schools built, renovated, or added onto from 1946 to 1973 were surveyed. Sprayed-on materials from the public areas of these schools were analyzed for asbestos content. Air samples were collected from 173 schools positively identified for asbestos. Most of the air sampling results were below the predetermined background noise level of 0.04 fibers per cc. It was concluded that it is not possible to quantify public exposures to asbestos because of the limitations of air sampling technology. A rating system was devised which generated a single number known as the Ferris Index which reflected the sprayed-on material's degree of potential health hazard. Data from five predictor variables were incorporated in this index. Although sprayed-on asbestos was present in 12 percent of the surveyed schools, only 3 percent required long-term control recommendations.