Rapport från Riksantikvarieämbetet 2006:3 Between 1989 and 1995 the National Heritage Board in Sweden managed and directed the ambitious 'Air Pollution and the Cultural Heritage' programme. This programme resulted in a nationwide inventory of building stones from early medieval times until the 1940s. After that, few attempts have been made to evaluate the result. The purpose of this particular study project is to improve the evaluation of stone conservation in Sweden using NDT methods that provide comparable quantitative data. The overall aim of Step 1 - the literature study - is to assess which NDT field methods can be used in stone conservation.