MEASUREMENT AND ASSESSMENT OF INDOOR AND OUTDOOR AMBIENT RADIATION LEVELS AT THE TAKE-OFF SITE
ABSTRACT
Harmful background radiation in our environment has been identified as one of the primary causes of various ailments such as cancer and tumors in our society today. These Higher radiation levels are emitted from igneous rocks such as granite rocks and soil formed from the weathering of these rocks as well as Radon gas in the atmosphere while lower radiation levels are usually associated with sedimentary rocks. This research project is aimed at the measurement and assessment of ambient indoor and outdoor radiation levels at the take-off site of Federal University Dutsin-Ma to ascertain the amount of ionizing radiation present. The indoor and outdoor radiation levels were measured in thirty-six (36) buildings, some road pavements and outdoor sports facilities are also considered using a digital radiation detector (Radiation Alert Inspector). While taking measurement readings, the radiation meter was held one meter above the ground oriented vertically upward. For each location, ten readings were taken, five indoors and five outdoors. From the results obtained, it was observed that the old Biology and Biochemistry laboratories were found to have the highest value of indoor annual equivalent dose rate of 2.27±0.29 mSv/yr and 2.27±0.33 mSv/yr respectively, while the lowest value for indoor annual equivalent dose rate was recorded as 0.85±0.22 mSv/yr at Lecture Halls 3 and 4. The highest outdoor annual equivalent dose rate was recorded at new Physics laboratory as 0.46±0.10 mSv/yr while the lowest outdoor annual equivalent dose was recorded at the recreational building as 0.23±0.03 mSv/yr. The overall average indoor and outdoor annual equivalent dose rates on the take-off site of FUDMA were computed and found to be 1.41±0.29 mSv/yr and 0.33±0.08 mSv/yr respectively. A comparison of these results with the worldwide average limit of equivalent dose rate of 2.4 mSv/yr recommended by the International Commission on Radiation Protection (ICRP, 1990) for protection of human beings from ionizing radiation, infers that the ambient indoor and outdoor radiation levels at the take-off site of FUDMA are within the safety limits. It is recommended that a further research should be carried out during the dry and rainy season using different radiation detectors and qualitative elemental analysis of the air, soil, water rocks and water be carried out so as to determine the actual radionuclides responsible for the levels of ambient radiation on the take-off campus of Federal University Dutsin-Ma.
CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Radiation is any form of energy propagated as rays, waves, or stream of particles which could be ionizing and non-ionizing. Ionizing radiation produces ionization when it passes through matter and is more harmful than non-ionizing radiation (IAEA, 1986). Ionizing radiation is that type of radiation which is able to produce ions that is capable of disrupting life processes. Non ionizing radiations are not able to create ions, although they may adversely affect human health in other ways. Man is by the very nature of his environment exposed to varying amounts of ambient radiation with or without his consent. The ambient radiation encompasses both the natural and man-made (artificial radioactivity) ionizing radiation in the environment (Farai and Vincent, 2006). Natural radioactivity has great ionizing radiation effect on the world population due to its presence in our surrounding at different amounts. Natural radioactive materials are found in rocks, soil, air, food and drinking water.
The natural environment therefore is a major source of radiation to which man is exposed. Ionizing radiation from natural sources that we are all exposed to at all times is called natural background radiation. Man-made radiation is generated in range of medical, commercial and industrial activities. The most familiar and, in national terms, the largest of these sources of exposure is medical X-rays (Hunt, 1987). We are all exposed to ionizing radiation from natural sources at all times. Natural background radiation is inevitably present in our environment (Hunt, 1987). Levels can vary greatly. A lot of our natural exposure is due to radon, a gas which seeps from the earth crust and is present in the air we breathe. The main sources of natural radiation are the following: terrestrial radiation, soil, gas, cosmic radiation and natural radioactivity in the body (Osiga, 2014). International Commission on Radialogical Protection (ICRP, 1990) set worldwide annual equivalent dose rate of ionizing radiation to 2.4 mSv/yr limit for protection of human being. At high doses, ionizing radiation is dangerous. The geology of Dutsin-Ma in which the school is situated, reveals that it is highly enriched in granite rocks. The specific levels of radiation are related to the types of rock from which the soils originate. Higher radiation levels are associated with igneous rocks, such as granite, and lower levels with sedimentary rocks (Sadiq and Agba, 2012). It is therefore necessary to know the level of radiation within our living environment because of its health implications to life.
1.2 Aim and Objectives of the Study
In line with the study problems stated above, the aim of this work is to measure and analyze the indoor and outdoor ambient radiation levels at the take-off campus of Federal University Dutsin-Ma, Katsina State. The specific objectives of this study are:
i. To measure the ionization radiation in and outside the buildings of Federal University Dutsin-Ma take-off campus.
ii. To compute from the data of the field radiation measurements the annual absorbed dose in the air and the distribution of effective dose in land and buildings in milliSeviet per year (mSv/yr).
iii. To compare and check the safety of human beings as a result of the computed radiation distribution for the study area using the ICRP (1990) worldwide average equivalent dose rate of 2.4 mSv/yr for human being protection as basis.