There has been much recent commentary about the 'third wave' of asbestos-related 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.