Airborne asbestos levels in buildings: maintenance worker and occupant exposures.

A substantial number of air samples have been collected during the past few years to measure airborne asbestos levels in buildings with asbestos-containing materials (ACM). These samples fall into two categories: (i) samples collected to measure the exposure of workers while they were engaged in routine maintenance and repair activities; and (ii) samples collected during normal building activity to measure prevalent levels in buildings. The measurements derived from these samples have been compiled and summarized to provide estimates of the airborne asbestos exposure of workers engaged in routine maintenance and repair work and by other building occupants. These data indicate that maintenance and repair workers in buildings with ACM, after accounting for the frequency and duration of these types of activities, have annual exposure levels ranging from a median value of 0.002 fibers per cubic centimeter (f/cc) per year to 0.02 f/cc per year at the 90th percentile. Building occupants not involved in maintenance and repair work experience average exposure levels ranging from 0.00003 f/cc to 0.0005 f/cc.