en Medical Physics Medical Physics تحقيق بديع Original Research <div style="text-align: justify;">Background: Radon is one of the most important radionuclides, formed from the decay of the element radium and more soluble in water. As drinking water is a vital source of life, control of its quality is critical. Drinking water containing high radon levels presents a serious risk to human health. Thus awareness of radon levels in drinking water is extremely significant to protect against radiation exposure. We measured ²²²Rn concentrations in different types of drinking water from Qena city, Egypt. Materials and Methods: 111 water samples were collected from various sources in Qena city (77 samples of household tap water, 14 samples of bottled water and 20 samples from municipal public water supply locations). The ²²²Rn concentrations were determined using an AlphaGUARD radon gas analyzer. We calculated annual effective dose due to ingestion and inhalation of ²²²Rn present in these waters. Results: ²²²Rn concentration ranges were as follow: 22.0&plusmn;0.7 to 118&plusmn;3 mBq l^-1, from tap water 14&plusmn;3 to 237&plusmn;5 mBq l^-1 from bottled water and 6.0&plusmn;0.5 to 30.0&plusmn;0.9 mBq l^-1 from municipal public supplies. The annual effective dose due to inhalation and ingestion of ²²²Rn in all types of drinking water measures less than the recommended reference level of 100 &micro;Sv y^-1. Conclusion: Based on the obtained results, ²²²Rn concentrations in the studied water samples were less than the permitted concentrations of USEPA and WHO guidelines.</div> 222-Rn, AlphaGUARD, , Annual effective doses, Bottled water, tap water. 227 233 http://ijrr.com/browse.php?a_code=A-10-2055-7&slc_lang=en&sid=1 S.D. Khaled ksh272@yahoo.com 7900319475328460015269 7900319475328460015269 Yes Department of Physics, Faculty of Science, South Valley University, Qena 83523, Egypt A.M. Khaled 7900319475328460015270 7900319475328460015270 No Department of Physics, Faculty of Science, South Valley University, Qena 83523, Egypt R.H. Shaban 7900319475328460015271 7900319475328460015271 No Department of Physics, Faculty of Science, South Valley University, Qena 83523, Egypt A. Abdel Baset 7900319475328460015272 7900319475328460015272 No Department of Physics, Faculty of Science, South Valley University, Qena 83523, Egypt