Indoor natural radiation levels in Ireland

The principal results of a preliminary study made on indoor radiation levels in Ireland are presented. During the period 1983-84 measurements were made in over 250 houses. Most measurements were made using passive devices: TLDs for penetrating radiation and CR-39 alpha track plastic detectors for radon measurements. The median value of the doses from penetrating radiation was 0.78 milligray/year with a maximum value of 1.47 m Gy/year detected. The radon concentrations showed a large degree of variability with a median value of 43 Bq/m3. About 10% of the houses had radon air concentrations in excess of 100 Bq/m3 with a maximum of 700 Bq/m3 being recorded. A tentative analysis of the data with regard to the geological situation is presented.