Asbestos Operation and Maintenance Studies on Carpet Cleaning, High Efficiency Particulate Air Vacuum Use, and Tile Buffing

Abstract

The U.S. Environmental Protection Agency's Risk Reduction Engineering Laboratory has conducted several research studies on the effectiveness of control measures for operation and maintenance activities in asbestos-contaminated buildings. Studies have been conducted on carpet cleaning, bag changing activities of portable high efficiency particulate air (HEPA) filter vacuums, and vinyl asbestos floor tile maintenance practices. In the carpet cleaning studies, hot water cleaning, HEPA vacuuming, and conventional vacuuming were compared. All three processes resulted in the release of asbestos into the surrounding environment as measured by transmission electron microscopy (TEM); however, none of the worker levels exceeded the Occupational Safety and Health Administration (OSHA) standard as measured by phase contrast microscopy (PCM). In the HEPA vacuum bag changing evaluation, all units tested exposed the worker to elevated asbestos concentrations, emphasizing the prudence of using protective clothing and respirators while performing this task. In the floor tile maintenance study, buffing activities resulted in increases in airborne asbestos levels in 12 of 17 school sites studied; the increase was statistically significant in seven of those sites, with TEM levels as high as four structures/ cc. PCM levels exceeded 0.1 fiber/cc in five of these. Although the workers often received undesirable exposures, the durations of the tasks were not long enough to exceed the OSHA 8-hour time-weighted average limit.