Assessment of indoor radon levels and associated hazards: effects of floor levels in residential buildings

The indoor radon concentrations in rooms of different floors in Irbid city in Jordan ranged from 8 to 50 Bq m−3 with an annual mean of 23 Bqm−3, which is less than the recommended action level. The average values of indoor radon concentrations in all investigated dwellings for basement floor, first floor, second floor, third floor and fourth floor were 36.13, 27.85, 21.24, 15.83 and 12.86 Bq m−3, respectively. The average annual effective dose is 0.318 mSv y−1 which is within the safe limits. Risk of lung cancer from the chronic exposure of the inhaled radon progeny may cause lung cancer of 6 cases per year per million person in Irbid city. Despite that the lung cancer, which is attributed to radon inhalation, forms about 5.7% of the total lung cancers, it is still a small ratio compared to risk of lung cancer caused by cigarette smoking and other factors which is 94.3%.