Worker exposure to asbestos during removal of sprayed material and renovation activity in buildings containing sprayed material.

Contents and types of asbestos in fireproofing insulation materials sprayed on ceilings of 127 buildings throughout the U.S. were studied. Asbestos was found to be present in more than 50% of the buildings and chrysotile was the main component identified. Frequency distribution of airborne fiber concentrations was lognormal. During renovation activities by various workers, including sheet-metal workers, carpenters and electricians, average fiber concentrations at workers' breathing zones were less than 2 fibers/cc, but exceeded 0.1 fibers/cc. During removal of sprayed materials, workers were exposed to extremely high concentrations (average 16.4 fibers/cc) when dry methods were used. When wet methods were used during removal, the airborne fiber concentrations were sharply reduced to less than 2 fibers/cc.