According to the Working Environment Measurement Standards, we have been measured the concentration of radioactive substances (radioisotopes) in the air at working rooms for handling radioisotopes for two years. The detection limit values of total γ-emitter and total β-emitter are 3.7×10-6 and 3.4×10-7 Bq/cm3, which are lower than 0.5% of their concentration limits in air. In almost all facilities, none of such radioactivities were detected. In only few rooms, the concentration of 3H and 14C were slightly higher than the detection limits. In the case of our university, all data obtained represented the fact that the concentration of radioisotopes in the air at all the working rooms using radioisotopes has been kept far below the limit of regulation.
