Airborne Fiber Levels During Asbestos Operations and Maintenance Work in a Large Office Building

Abstract

While there is growing interest in the management of asbestos-containing materials (ACM) in buildings using operations and maintenance (O&M) programs, very little data are yet available on the effectiveness of such programs in reducing airborne fiber exposures of workers and other building occupants. This article presents and analyzes air sampling data collected in conjunction with O&M work over a 5-year period in a large Washington, DC, office building. ACM present in the building included pipe insulation, air handling unit insulation, acoustical ceiling plaster, and air supply ductwork. The database included 916 phase contrast microscopy (PCM) and 163 transmission electron microscopy (TEM) area samples. Seventy-six samples were analyzed by both methods. Overall, TEM and PCM concentrations averaged 0.0109 structures/ml (s/ml) for fibers longer than 5 μm (0.0035 s/ml after excluding two outliers) and 0.0059 fibers/ml, respectively. We examined fiber concentrations in several work activity categories (e.g., work above ceilings, pipe work, carpet removals) and as a function of proximity to the work area. We also analyzed the correlation between PCM and TEM analyses performed on the same filters. TEM concentrations were higher for pipe work than for either work above ceilings (p < 0.02) or carpet removals (p < 0.0001). PCM concentrations were higher for work above ceilings than for most other work categories. Peak concentrations tended to cluster within particular jobs, especially for PCM. Samples collected in work areas were statistically higher than samples collected outside of work areas for PCM (p < 0.001), but not for TEM. There was no correlation between TEM and PCM analyses of the same filter. The data reported in this article add substantially to the available literature on airborne fiber levels during maintenance work under O&M programs.