Estimation on the indoor radioactive level and exposure dose in an office building of a university in Tangshan city.

[Objective] To explore the indoor γ-ray dose rate, radon concentration and influence factors in an office building in Tangshan city, and estimate the per capita exposure dose in one year. [Methods] 1-2 offices of both sides (south and north) in each floor (2-4 floors) in an office building of a university in Tangshan city were selected. Indoor radon concentration, γ-ray dose rate of grounds and walls was measured respectively. [Results] The indoor average γ-ray dose rate of the grounds and the walls was 0.317±0.452 μGy / h and 0.192±0.263 μGy / h respectively. The mean of radon concentration was 9.43 Bq / m3. The average γ-ray dose rates of the grounds decorated different decorative materials (cement, marble, ceramic) were markedly different (P﹤0.01), and the marble ground was the highest. The annual per capita exposure dose was 1.72mSv·a-1. [Conclusion] The radioactive level of this office building and the annual per capita exposure dose are both safe. This study finds that the marble decorative materials may increase indoor radioactive level.