The objective of the present work was to assess the distribution of radon in the University of Technology buildings, Baghdad - Iraq and to identify the effective dose of radon exposure to the staff using passive dosimeter (SSNTD) CR-39. One hundred CR-39 dosimeters were distributed over different buildings in the University campus according to the number of floors area. The exposure time started from December 2012, and the dosimeters were left inside buildings for 40 days. Only 93 dosimeters were collected, while the remaining 7 were considered lost. The average concentrations were calculated in units of Bqm-3, for each sample in each building, and then are repeated after grouping in each floor of the same building. The average radon concentrations per building and at the university as a whole were also calculated.
Radon concentrations were found to vary from 80.1 to 416.7 Bqm-3. The highest radon concentration with a mean value of 416.7 Bqm-3 was found atuniversity press section building, while the lowest radon concentration was found at the welding division 2 building with a mean value of 80.1 Bqm-3. The average value of radon concentration at the university was found to have the value of 181.9 Bqm-3 which is less than the recommended value of 200 Bqm-3 UNSCEAR .
Dose rate (in µSv/h), annual dose rate (in mSv/y & WLM/y), cumulative dose (in mSv& WLM) and cancer risk were also calculated. It was found that the university staffs are exposed annually to 2.083 mSv which equal to 0.231 Working Level Month (WLM) from radon gas and its short-lived daughters. Hence, a person takes on the average an annual effective dose equivalent to 2.56and 1.84mSv according to average value considered by UNSCEAR  and ICRP , respectively. This implies an expected value for lung cancer probability of 0.0046.