An impact of floor levels and geological formation on the concentrations of indoor radon and its progeny studied inside 8 hospitals, and for three floor levels: ground, first and second. Locations of the selected hospitals had different geological formation and located in three main governorates: Erbil, Duhok and Sulaymaniya. Nuclear track detector type CR-39 (CR-39NTDs) used to measure track density of alpha particles that emitted from radon and its progeny. During winter season, 72 pair of exposure chambers (open-close chamber) equipped with 144 pieces of CR-39NTDs installed inside 24 rooms for three floors. After 90 day of exposure, exposed detectors etched in 6N NaOH at 70 ?¢????¦C for 10 h. The highest and lowest radon concentration was in the hospitals of Shaheed Aso (Sulaymaniya city: 131.73±9.42 Bq.m-3) and Erbil Teaching (Erbil city: 82.13±10.05 Bq.m-3) .This depended on the geological formation, type of building material, and the floor level. Therefore, the results showed that the average radon concentration and annual effective dose decreases gradually as the floor level increases. The highest and lowest of annual effective dose was found in ground and second floor, respectively. Thus, according to the annual exposure dose data, the workers are safety in most of the hospitals. More details about the type of building materials of the hospitals are listed in full paper.
