Statistical analysis of data on airborne asbestos levels collected in an EPA survey of public buildings.

Data from a recent EPA study of airborne asbestos levels in 49 buildings occupied by the General Services Administration (GSA) are statistically analyzed. The study focuses on differences between indoor and outdoor levels, and on differences among buildings with no asbestos-containing material (ACM) (6 buildings), buildings with ACM generally in good condition (6 buildings), and buildings containing damaged ACM (37 buildings). Seven indoor samples and a single outdoor sample were collected from most buildings and analyzed by TEM (transmission electron microscopy) using a direct preparation method. No statistically significant differences were detected in asbestos levels between indoors and outdoors or among the three categories of buildings. The average indoor concentration of asbestos was 0.00073 fibers/cc (f/cc) for all fibers and 0.00007 f/cc for fibers 5 microns or longer. The current OSHA occupational standard is 0.2 f/cc for fibers 5 microns or longer as measured by phase-contrast microscopy.