As with jet fuel, these elevated benzene concentrations were more likely to occur in foamed tanks. The instantaneous sampling results confirm that benzene exposures occur during fuel tank repair levels up to 49.1 mg/m3 were found inside the tanks during the repairs. Fuel tanks that allow flow-through ventilation during repair resulted in lower exposures compared to those tanks that have only one access port and, as a result, cannot be ventilated efficiently. It is assumed these elevations result from the tendency for fuel, absorbed by the foam, to volatilize during the foam removal process. The results indicate workers who repair fuel tanks containing explosion suppression foam have a significantly higher exposure to jet fuel as compared to workers who repair tanks without foam (p < 0.001). The highest eight-hour time-weighted average (TWA) fuel exposure found was 1304 mg/m3 the highest 15-minute short-term exposure was 10,295 mg/m3. In addition, instantaneous samples were taken at various points during the procedures with SUMMA canisters and subsequent analysis by mass spectrometry. Breathing zone samples were collected on the fuel workers who performed the repair. Jet fuel and benzene vapor exposures were measured during aircraft fuel tank entry and repair at twelve U.S.
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