Abstract Radon and its daughter concentrations have been measured in 64 living rooms of six residential and 31 rooms of three non-residential buildings. CR-39 solid state nuclear track detectors were used to measure the radon concentrations inside the rooms. It was found that the radon concentration in winter was 1.5± 0.5 times higher than in summer. Radon concentration was higher at the ground storey rooms than the first and second storey rooms. The average dose equivalent rate due to radon daughters for a person is found to be 0.37 WLM yr -1, using an equilibrium factor of 0.5 and an occupancy factor of 0.8.