Resuspension of Asbestos in Settled Dust in an Apartment Cleaning Situation

Abstract

To gain information about the airborne asbestos levels to which an apartment dweller could be exposed as a C1 occupant, a simulation exercise was designed to study the upper limit of normal cleaning activity. Prior to the cleaning exercise, settled dust samples were collected to establish an index of asbestos fibers with potential for release from the surfaces in the apartment; microvac dust samples were collected from six locations where dust was to be disturbed. The cleaning exercise consisted of vacuuming the complete floor surface of the apartment continuously for 30 minutes using a commercial vacuum cleaner, followed by dry wiping of all appropriate surfaces for 30 minutes. During the cleaning, exercise area and personal air samples were collected. Before cleaning, asbestos in air measured less than 3 asbestos structures/L. During cleaning, air samples in the vicinity of the breathing zone of the person cleaning were below detection of phase contrast microscopy (PCM) (<0.04 f/ml) and 40–140 s/L by transmission electron microscopy. Dust samples showed levels of asbestos in the range of 2000–7000 str/cm² except for one sample from the top of a gas heater. The index of asbestos in the settled dust, as determined by microvac test (weighted for surface area) was approximately 4000 str/cm². Results showed a trace of asbestos was suspended into air at below the detection level of the PCM analysis. The resuspension factor “K” value was calculated to be in the range of 10⁻⁵ cm⁻¹ using the average (personal) air sampling data and the average (area weighted) dust sampling data.