Airborne asbestos exposures associated with work on asbestos fire sleeve materials

► We measured airborne asbestos exposure from the servicing of aircraft fire sleeve. ► Worst case conditions that might occur in a mechanic’s work environment were used. ► Maximal average personal exposures were 0.025f/ml. ► Mechanics do not receive substantial asbestos exposure when servicing fire sleeve. Asbestos-containing fire sleeves have been used as a fire protection measure for aircraft fluid hoses. This investigation was conducted to determine the level of airborne asbestos fiber exposure experienced by mechanics who work with fire sleeve protected hoses. Duplicate testing was performed inside a small, enclosed workroom during the fabrication of hose assemblies. Personal air samples taken during this work showed detectable, but low airborne asbestos fiber exposures. Analysis of personal samples (n=9) using phrase contract microscopy (PCM) indicated task duration airborne fiber concentrations ranging from 0.017 to 0.063 fibers per milliliter (f/ml) for sampling durations of 167–198min, and 0.022–0.14f/ml for 30min samples. Airborne chrysotile fibers were detected for four of these nine personal samples, and the resulting asbestos adjusted airborne fiber concentrations ranged from 0.014 to 0.025f/ml. These results indicate that work with asbestos fire sleeve and fire sleeve protected hose assemblies, does not produce regulatory noncompliant levels of asbestos exposure for persons who handle, cut and fit these asbestos-containing materials.