ABSTRACT
A considerable number of settled dust analyses for asbestos using transmission electron microscopy have been performed following the microvac sampling procedure. Some data also exist for analyses of carpet using the bulk carpet sonication technique. The values of asbestos in the dust have been usually given in terms of asbestos structures per square foot or asbestos structures per square centimetre. Typical asbestos concentration values in the surface dust as determined using the microvac technique were published for a variety of sites containing asbestos-containing material's (ACM). Microvac dust samples from several government buildings which did not have ACM's in the State of Maryland showed levels of asbestos fibers less than 200 s/cm. In an office building with ACM's, samples were collected in a number of similar rooms in which the owner was able to document the last date that the cleaning service had cleaned that particular area.