Environmental risk assessment of radon from ceramic tiles

Radon-222 exhalation from different ceramic tiles depends upon the radium (226Ra) concentration and porosity. Raw zirconium sand is one of the substances widely used in the ceramic industry and it is naturally radioactive. This can produce unjustified concern and subsequently perturb the market of these products. The radon exhalation rates for all ceramic tile companies were in the ranges 28-44 mBq.m-2.h-1 and 2.0 to 4.8 mBq.kg-1 .h-1. The porosity of ceramic tiles is in the range 0.19-0.28. The radium activity of ceramic tiles was found to be in the range 16-38 Bq.kg-1 for the glazed surface and 23-64 Bq.kg-1 for the clay surface, respectively. The average equivalent dose in contact with the ceramic surface was found to be 22 mSv.y-1. The exposure at working level at the ceramic tile surface was in the range 2.4-3.8 WL. This gives a risk indication to people who spend a long time in closed ceramic tile stores, who should avoid staying for a long time in such places. (authors)