Baseline Studies of Asbestos Exposure During Operations and Maintenance Activities

Abstract

Eight simulations of installation, repair, remodeling, and maintenance tasks in buildings with asbestos-containing material (ACM) were conducted to investigate worker exposure to airborne asbestos. Since the tasks were performed using typical custodial and maintenance procedures without regard to the presence of ACM, the results contribute to establishing exposure baselines for custodial and maintenance workers. These baselines can also be used to judge the effectiveness of special operations and maintenance programs designed to minimize asbestos exposure in buildings which contain asbestos materials. Six different types of tasks (moving an office wall, cleaning a storage area, replacing ceiling tile, repairing/installing electrical fixtures, repairing plaster, and removing carpet) and two types of ACM (fireproofing and acoustical plaster) were included in the eight simulations. Exposure was measured by monitoring levels of airborne asbestos before, during, and after the task (and for two simulations, during a subsequent cleaning phase). Both area and personal air samples were collected. All samples were analyzed by transmission electron microscopy following an indirect sample preparation; personal samples collected during the simulated tasks were also analyzed by phase contrast microscopy. Differences in airborne asbestos concentrations among the various study phases were compared using analysis of variance following a lognormal transformation of the data. Results for seven of the eight experiments showed that airborne asbestos was significantly elevated by the task simulated and, where worksite cleanup was a separate phase, by the cleaning activity. Ratios of concentrations of total asbestos fibers counted during the simulated task to those counted before the start of work ranged from 36 to almost 9400, with a mean of approximately 2000. These results indicate that custodial and maintenance work around or with ACM may significantly increase worker exposure; the use of special work practices to reduce fiber release and respiratory protection to reduce worker exposure are recommended.