Radiological environmental studies of Al Aziziah area and vicinity, Al Madinah Al Monawarah, Saudi Arabia.

The Al Aziziah area is built on volcanic and granitic rocks. The igneous rocks always contain a high amount of naturally radioactive elements such as uranium, thorium and potassium, which produce gamma rays causing environmental hazards when exceeding the permissible limit. Radon gas is a result from the decomposition of uranium/thorium leaks into enclosed areas (e.g. homes or offices). This leakage is controlled by many conditions, and one of them is the underlining rock type. To work on such an environmental study, a gamma ray spectrometer survey was used. The uranium, thorium and potassium contents, as well as their ratios and the total radiation, were determined and mapped. The radiation dose rate was calculated and mapped in mSv/y and nGy/h units. The radiation contamination of groundwater is detected from the contour map of the dose rate over the artificial drainage lines of rains and floods which move this water to the groundwater wells. The main results are as follows: granitic rocks show an average dose rate of about 2.4 mSv/y, while the deposits of these rocks have an average dose rate of 1.2 mSv/y. A low average dose is recorded over the basalt. The average radiation dose recorded in the study area is 1.08 mSv/y, while its range is from 0.001 to 4.41 mSv/y. The estimated effective doses within the Al Aziziah area and vicinity area were higher than 1 mSv/y, which is the public exposure limit, and lower than the occupational exposure limit of 20 mSv/y. We recommend ventilating homes and offices in these places on an ongoing basis and constant radon measuring in closed places.