Measurement of Background Radiation Levels in Some Selected Automobile Mechanic Workshops in Freetown

Radiation is a natural and unavoidable part of the environment, emanating from both natural and artificial sources. Among the various forms of radiation, gamma radiation holds particular significance due to its high energy and deep penetration capability, which can have profound effects on human health and the environment. This research investigates the background gamma radiation levels in selected automobile mechanic workshops in Freetown, Sierra Leone, to address concerns about unintentional exposure to high quantities of ionizing radiation, particularly gamma rays. A handy automess 6150 AD 6/H survey metre was deployed to determine the exposure level of the workers and people around these automobile mechanic workshops to gamma radiation. The research showed that the highest annual equivalent dose rate is 2.081 mSv/yr and the lowest annual equivalent dose rate is 1.834 mSv/yr. These values exceed the annual dose limit of 1.0 mSv/yr as recommended by major international organizations like the ICRP, IAEA, and UNSCEAR. However, the outside background radiation exposure in the selected areas varies between 0.0124 and 0.0189 mR/hr, making an average of 0.0154 mR/hr in the surroundings, which also marginally exceeds the benchmark outside background radiation value of 0.011 mR/hr established by the U.S. NRC. The research suggests that the placement of these automobile mechanic workshops may have been influenced by nearness to radiation sources, which could pose serious health risks over time. Therefore, the workers, residents and the surrounding area are at the risk of chronic radiological effects due to long-term exposure.