Tesfaye, Tilahun (PhD)Berhane, Tsega2018-07-092023-11-092018-07-092023-11-092007-08http://10.90.10.223:4000/handle/123456789/7157Suction pump was used for air to pass through a glass filter (> 90% filtration efficiency) and aerosols were deposited on it. The sampled filter was placed below a GM tube (with GM nuclear counter) within a time interval of less than one minute after sampling, and gross ¯ counts were registered in successive time interval for more than six to ten hours. Determination of activity concentration of progenies of 222Rn and EEC (equilibrium equivalent concentration) of 222Rn was done by fitting the observed gross ¯ count to a mathematical model. The indoor and outdoor variation of 222Rn was observed inside and outside of the nuclear physics laboratory (around four meters above the ground). The average EEC of 222Rn was found to be 23.9 Bq=m3 and 3.74 Bq=m3 for indoor and outdoor respectively. Indoor radon concentration is 4 to 6 times higher than the outdoor. Our result agrees with the results available in other studiesenRadon ConcentrationThesis