October 8, 1998
An inspection of a roof repair project on a government building revealed that the concrete material used for forming the roof surface in 1934 contained a high concentration of asbestos.
The asbestos/concrete mixture is called "soft concrete." Apparently, when the government building was built, asbestos was mixed with concrete to make a lighter and easier to use mixture than regular concrete. It was then used for creating the slopes on the roof. The soft concrete layer ran between two and 10 inches in thickness on the roof of the inspected building.
The roof repair work required the removal of the roofing tar paper and the soft concrete layer. The construction contractor investigated for the presence of asbestos prior to work beginning at the site. Although no asbestos was found in the tar paper, analysis of the concrete revealed it had an asbestos content of between two and 10% by weight. Therefore, it had to be handled as asbestos containing material since the asbestos content exceeded 1% by weight.
The removal of this type of soft concrete is a task that requires extensive precautions and control methods as prescribed by OSHA Construction standard 29 CFR 1926.1101(g), Methods of compliance, and the revised 29 CFR 1926.1101(h), Respiratory protection. Other sections of 29 CFR 1926.1101 are also applicable.
However, OSHA has no data on how many buildings might have soft concrete on their roofs. It is possible that such a mixture was used on other roofs and, therefore, its presence could pose significant health hazards during demolition or repair work. Furthermore, employees occupying a building might be exposed to the asbestos from the roof's materials if there are openings in the building, particularly during reroofing work. Therefore, prior to beginning work, it is necessary to exercise reasonable diligence to assess the presence of soft concrete and the potential exposure risk.
Please distribute this bulletin to all area offices and appropriate industry and labor groups.
1 The Directorate of Technical Support issues Hazard Information Bulletins (HIB) in accordance with OSHA Instruction CPL 2.65 to provide relevant information regarding unrecognized or misunderstood health hazards, inadequacies of materials, devices, techniques, and safety engineering controls. HIBs are initiated based on information provided by the field staff, studies, reports and concerns expressed by safety and health professionals, employers, and the public. Bulletins are developed based on a thorough evaluation of available facts and in coordination with appropriate parties.
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