Weathering of asbestos cement: Do old asbestos roofs release fibers?
The ban on asbestos has been in effect in Germany for almost 30 years. This also means that common asbestos products such as fiber cement have been exposed to weathering since that time, especially on the exterior. What this means for the material and the eventual release of fibers has now been explored by a Norwegian research team [Ervik et al. 2021].
For this purpose, samples of asbestos cement roofs around 50 years old were examined. Asbestos fibers were found both in the vegetation and in water samples from the gutters. In addition, exposed weathered fibers were found on the weather side of the asbestos cement, while these were not observed on the protected undersides.
Parallel air samples taken downwind of the roofs were unremarkable. Presumably, the exposed weathered fibers are mobilized mainly by rainwater.
Even though the results strictly apply to the climatic conditions in Norway and the roofs investigated were about 50 years old (in Norway, a ban on asbestos cement as roofing has been in force since 1984), a lot can be learned here about the long-term behavior of this roofing. In principle, the findings should also be applicable to other countries such as Germany, where asbestos roofs have also been exposed to the weather for decades.
A more detailed discussion of "Weathering of Asbestos Roofs" has been published by our colleague Dr. Gunnar Ries in a comprehensive technical blog entry at scilogs.spektrum.de.
The original study:
Ervik, T., Eriksen, S. & Graff, P., Mobilization of asbestos fibers by weathering of a corrugated asbestos cement roof, Journal of Occupational and Environmental Hygiene, 18 (3), 110-117, 2021.