Assessment of Background Radiation Levels in Gombe Metropolis, Gombe State, Nigeria

Exposure to ionizing radiation is known to be responsible for certain health disorders such as cancer, cataracts and birth defects and humans are inevitably exposed to radiation which could be from either Natural or Man-made sources. For this reason, several international bodies have worked on standards in relation to radiation hazards and this has led to the establishment of maximum permissible dose limits (MPL) of 1Msv/yr for non-occupational exposure. This study assesses the background radiation level of Gombe metropolis of Gombe State in other to determine the effective dose of the area and compare the values obtained with maximum permissible dose limits (MPL). A total of twenty points were surveyed using a portable Geiger Muller LND 7223 radiation survey meter (GM Counter). At each measurement point, three readings in Count Per Minute (CPM) were taken with the Geiger Muller counter held at one meter above the ground and the average is taken as the mean Count Per Minute. The mean Counts per Minute obtained were converted to Exposure rates in mR/hr, Absorbed Dose rate in nGy/hr and Annual effective doses in mSv/yr. The exposure rate ranges from 7.2μR/hr to 12.5 μR/hr with a mean value of 9.3μR/hr. The absorbed dose obtained ranges from 62 nG/hr to 102 nGy/hr with mean of 78 nGy/hr which is slightly higher than the world average 55nGy/hr. The annual equivalent dose rate for indoor ranges from 0.316 to 0.512 with an average of 0.333 mSv/yr while the outdoor annual equivalent dose rate ranges between 0.079 to 0.128 mSv/yr with an average of 0.099 mSv/yr. These values are lower than the internationally approved annual dose limits of 1mSv/yr for members of the public by International Commission on Radiation Protection [ICRP]. Hence, it is concluded that there are no significant risks from harmful radiation exposure in Gombe metropolis.