[en] In the United Kingdom, the estimated average annual effective dose equivalent to members of the public from all sources is 2.4 mSv (240 mrem). 40% of this dose is contributed by exposure to radon, and it is not unreasonable to assume that the situation in Ireland is very similar. During 1982-84 a preliminary study of radon and penetrating radiation on 300 Irish houses showed seasonally averaged indoor radon concentrations in the range 3 Bq/m³ of air to 700 bq/m³, with a median value of about 40 bq/m³. A national survey of indoor radon has now been undertaken; 3000 households, randomly selected from the electoral register are to be monitored and the result correlated with energy conservation practices. The final part of this document deals with the regulatory aspects of radon control and reviews the practices for reduction of indoor radon daughter doses presently in hand in Scandinavia. An appendix of radiation units and terms is also given