The damage functions discussed in Chapters 3 and 4 can be used to assess the impact of pollution by calculating the rate at which a given material will corrode or soil. If it is desirable for policy development to estimate a regional impact, there is one other vital data component required, which is an estimate of the amount of each material being affected that is known as the stock at risk. This vital area remains seriously under-researched, mainly due to the high cost and complexity of compiling inventories. To date actually, there are no stock-at-risk estimates of any heritage materials at a continental level. Some research groups and institutions have tried to develop maps of heritage at risk in different countries, frequently based on different criteria, choosing different parameters of risk and materials. © 2009 Springer-Verlag US.