Results of a survey on radioactivity of building materials in Italy.

A program is underway in Italy to identify construction materials with high radioactivity contents and to evaluate the resulting indoor exposure on a nationwide scale. Building materials surveyed include those of natural origin and those employing particular by-products such as fly ash and phosphogypsum. The survey currently emphasizes natural building materials, which are widely used in many areas having particular geological features. First results show that Italy includes areas of high natural background, i.e. in Lazio and Campania, in which very high levels of indoor exposure occur that can be directly related to specific activities of the building materials. Moreover, 220Rn daughters are sometimes present at such levels that their contribution to the lung exposure is comparable to that from 222Rn daughters.