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3652310 
Journal Article 
Baseline Studies of Asbestos Exposure during Operations and Maintenance Activities 
Keyes, DL; Ewing, WM; Hays, SM; Longo, WE; Millette, JR 
1994 
Yes 
Applied Occupational and Environmental Hygiene
ISSN: 1047-322X
EISSN: 1521-0898 
NIOSH/00225599 
9 
11 
853-860 
Exposure to airborne asbestos (1332214) fibers was measured for six types of standard operations and maintenance tasks in buildings where chrysotile (12001295) asbestos fireproofing or acoustical plaster was present. Eight experiments were performed by industrial hygienists/environmental consultants. No special asbestos related procedures were followed other than protecting the experimenters. Area air samples were collected before, during and after tasks. The during phase included cleanup (except for experiments three and four, in which a separate cleaning phase was included after the 2 to 3 hour after phase). The samples were analyzed by transmission electron microscopy (TEM). Personal samples were collected in the during phase (and, for experiments three and four, the cleanup phase); these were analyzed by both TEM and phase contrast microscopy (PCM) using NIOSH Method 7400. Ratios of airborne asbestos concentrations in the during versus after phases were determined (and for cleanup versus before for experiments three and four) for all asbestos structures counted. The increase averaged 1.50 structures/milliliter and ratios ranged from 36 to almost 9,400 (mean approximately 200), which were significant, except for experiment six involving fixture removal and reinstallation. The other task simulations were: moving an interoffice wall, cleaning dust using dry methods, removing and replacing ceiling tile, cleaning and inspecting light fixtures, repairing damaged plaster, and cutting and removing carpet. In experiments three and four, cleanup generated higher asbestos concentrations than the tasks themselves (ceiling tile replacement and light fixture maintenance). Generally, personal sample concentrations were higher than area sample concentrations. The authors note that differences in measured concentrations by TEM and PCM highlight the insensitivity of PCM to very thin fibers and suggest using TEM. They recommend respirators and special work practices for all maintenance, repair, and installation personnel in the presence of asbestos containing materials.