eng Science and Education Publishing International Journal of Physics 2333-4576 2015-11-09 3 6 233 238 10.12691/ijp-3-6-2 IJP2015362 article Nada Fadhil Tawfiq laith_najam@yahoo.com 1 Hazim Louis Mansour 2 Mahmood Salim Karim 2 Department of Physics, College of Science, Al-Nahrain University, Baghdad, Iraq Department of Physics, College of Education, Al-Mustansiriyah University, Baghdad-Iraq In the present work, we have measured the radon gas concentrations in tap water samples for selected regions (some of them were measured for the first time as far as authors know) in Baghdad governorate by using alpha-emitters registrations which are emitted from radon gas in (CR-39) nuclear track detector. The results of measurements have shown that the highest average radon gas concentration in tap water samples was found in B16 (AL-Zafraniya) region, which was equal to (0.190±0.01 Bq/L), while the lowest average radon gas concentration was found in B20 (AL-Karada) region, which was equal to (0.073±0.01 Bq/L), with an average value of (0.135±0.03 Bq/L). The highest value of annual effective dose in tap water samples was found in B16 region, which was equal to (0.694 uSv/y), while the lowest value of annual effective dose was found in B20 region, which was equal t (0.267 ̦Sv/y), with an average value of (0.493±0.12 ̦Sv/y). The present results have shown that radon gas concentrations in tap water samples were less than the recommended value (11.1 Bq/L) given by (USEPA,2012). There for tap water in all the studied sites in Baghdad Governorate is safe as for as radon concentration is concerned. http://pubs.sciepub.com/ijp/3/6/2/ijp-3-6-2.pdf tap water radon concentration CR-39 nuclear track detector