Background: The value of indoor radon concentrations is related to the health of public

the measurement and evaluating had been attracting much attention from the scientific researcher. Purpose: The aim is to measure the indoor radon concentrations in a laboratory of university located in Chengdu

and estimate the annual effective dose of radon for researcher and staff. Methods: The measuring site and estimating dose were chosen according to the requirement of Specifications for monitoring of indoor radon and its decay products (GBZ/T 182-2006). Results: The average radon concentration in the laboratory building is 20.99±13.87 Bq?m?3

which is conforming to the demands of Basic standards for protection against ionizing radiation and for the safety of radiation sources; the value of indoor radon concentrations is related to the area of the room. The annual effective dose of the science researchers in the laboratory building is 0.24 mSv

which is lower than the world average dose. Conclusion: The annual effective dose of radon people in the laboratory received is in the normal background level; radon and its daughter don’t bring additional dose. The instrument measuring radon in balloon method is simple in operation and portable; as direct scale based on the instrument can calculate the calibration factor without standard radon chamber

in the range of error

the calibration factor can satisfy the need of actual work. Abstract