Airborne asbestos levels in several school buildings before and after bulk asbestos removal

Airborne particulate samples were collected in several public schools before and after friable asbestos containing (5–20 percent) insulation material had been removed from the ceiling areas. Transmission electron microscopy with selected area electron diffraction (SAED) was used for fiber identification and counting. Asbestos fiber concentrations in the air were in the range 5–40 ng/M³ before removal of the friable asbestos ceiling insulation. The airborne asbestos concentrations approximately one week after removal showed reductions of 56 to 90 percent.