Airborne Asbestos Concentrations during Abatement of Floor Tile and Mastic: Evaluation of Two Different Containment Systems and Discussion of Regulatory Issues

Abstract

Regulatory agencies in the United States identify asbes tos-containing floor tile as a friable material when abated. Such categorisation appears to be based on legislation rather than science and exposure data or health risks. This investigation suggests that occupation al (personal) exposure during abatement of floor tile and mastic results in low airborne concentrations of asbestos as determined by phase contrast microscopy. Compari son of personal exposure results for two asbestos abate ment school projects, which collected exposure data dur ing abatement of floor tile and mastic together, one involving full containment and the other a partial con tainment system (critical barriers), suggests a statistical difference in concentrations. However, this difference was not considered to be biologically (health) significant. Other studies that collected exposure data on floor tile and mastic separately support findings of low exposure in studies reporting measurements of these building components together. Summary results as arithmetic and geometric means for occupational samples were below the Occupational Safety and Health Administra tion permissible exposure limit for airborne asbestos fibres. The basis for classifying floor tile and mastic as a friable asbestos-containing material does not appear to be supported by scientific evidence. A discussion of reg ulatory issues associated with asbestos-containing floor tile and mastic is presented.