Comparison of indoor levels of radon between workplaces and homes located nearby in different parts of Finland.

The aim of this study was to compare the radon levels at workplaces and in homes located nearby. Homes (number of 57) and partly or fully underground workrooms (number of 55) have been studied at the four workplaces in southern Finland and one workplace in northern Finland. Radon concentrations both at workplaces and in homes seemed to be at the same level in the same district. The mean radon concentration in workrooms was 406 Bq.m³, and in homes concentration was 398 Bq.m³. At the workplaces having mere exhaust ventilation the mean radon concentration was higher (arithmetic mean of 677 Bq.m³, n=14), than the places having mechanical exhaust and supply ventilation (arithmetic mean of 207 Bq . m³, n~=3,3 ). In an average the naturally ventilated workplaces (n=8) had the lowest level of indoor radon (arithmetic mean of 133 Bq.m³). The highest radon level, both in the workrooms (2937 Bq.m³) and in the homes (3080 Bq.m³), was found in the northern Finland. The high values of indoor radon might be partly explained by the hill-construction of buildings without sealed constructions against soil, and partly by depressurisation caused by mechanical exhaust ventilation.