Airborne Asbestos Fibers in a Building After Remedial Actions on Sprayed Asbestos-Containing Materials

Abstract

Buildings at a university in Paris, first examined 15 years ago, were re-evaluated in 1989 to assess the effectiveness of remedial action directed against sprayed-on asbestos materials. Twenty indoor samples and 2 outdoor samples were collected. These included 15 sites common to the two studies. The levels of airborne asbestos fibers were determined by transmission electron microscopy using an indirect preparation method. A comparison of fiber levels in 1975 and 1989, at different sites, with and without remedial action, was performed using mass and numerical concentrations. Although the number of samples in the current study was limited, the 1989 results showed a significant reduction in the concentration of airborne asbestos fibers in comparison with findings from the earlier study. In 1975, indoor asbestos concentrations varied from 1 to 750 ng/m³; in 1989, the concentrations varied from less than 0.1 to 39 ng/m³ (while the concentrations of fibers longer than 5 μm varied from less than 0.0001 to 0.0273 f/ml). The most marked decrease appeared to occur when an important remedial action had been undertaken, but a reduction of the air concentrations was also observed at sites without any remediation. Even in the absence of removal of asbestos-containing material, the measurement data indicated that, in all locations in which effective remediation had been performed, the fiber levels had decreased, with no sample exceeding 50 ng/m³. It must be noted that the same results were observed at most other sites, emphasizing the importance of good prevention, informing building occupants and modifying cleaning procedures. However, because the degradation of asbestos-containing materials can occur, a rational surveillance program of asbestos pollution is required. Moreover, the risks for custodians and maintenance workers persist and justify appropriate medical surveillance.