Urban dose rates at Gavle, Goteborg and Lund

Besides gamma rays from Cs-137 emanating from the Chernobyl accident, gamma rays from natural radionuclides are a dominant source of radiation exposure to the public. Since people spend much more time indoors than outdoors the radiation dose obtained inside dwellings contributes greatly to individual and collective doses. Dose rate measurements were made at 20 locations within the city of Goteborg and at further 22 reference sites within a radius of 100 km. Measurements were also made at Gavle and Lund. The dose rates were measured with RNI intensimeters, TLD (LiF) meters and in in situ measurements using an HPGe. The ground cover was grass. asphalt, concrete slates or paving-stones. The dose rates varied between 0.05 and 0.25 mu Sv/h. Also performed in different ways, measurements made inside and outside buildings at both Goteborg and Gavle showed inside dose rates higher than outside dose rates.