There has been much recent commentary about the 'third wave' of asbestosrelated disease, arising particularly from exposures of people repairing, renovating or demolishing buildings that contain asbestos. The presence and extent of a third wave, however, are difficult to assess, and the extent and risk of both occupational and nonoccupational third-wave exposures are largely unmeasured. Moreover, we lack information on the extent of deterioration of in situ asbestos, and its significance for ambient and third-wave exposures. This paper considers the available evidence about the third wave. It proposes approaches to obtaining the information needed to properly estimate the risk of third-wave exposures, and guide actions that will crest a likely third wave with minimum harm and cost to the community.