Radioactive radiation is a form of ionizing radiation produced by unstable atoms when their nuclei undergo spontaneous disintegration. It has sufficient energy to remove electrons from atoms and molecules, thereby producing ions. Radioactive radiation occurs naturally in the environment and is also generated through human activities. In environmental health, understanding its sources and harmful effects is important because prolonged or excessive exposure can damage living tissues, cause disease, and affect future generations. The sources of radioactive radiation can broadly be classified into natural and artificial sources. Natural sources have existed in the environment since the formation of the Earth, whereas artificial sources are associated with medical, industrial, agricultural, scientific, and nuclear activities. Natural background radiation is the largest source of radiation exposure for most people. Cosmic radiation originates from outer space and reaches the Earth continuously. The intensity of cosmic radiation increases with altitude because the atmosphere provides less shielding at higher elevations. Therefore, people living at high altitudes and individuals who frequently travel by air receive somewhat greater exposure. Terrestrial radiation is another important natural source. Rocks and soil contain naturally occurring radioactive elements such as uranium, thorium, radium, and potassium-40. Their radioactive decay releases radiation into the surrounding environment. Certain geological formations contain higher concentrations of these elements, resulting in greater background radiation in particular regions. Radon is a particularly important environmental source of radioactive exposure. It is a radioactive, colourless, odourless and tasteless gas produced naturally during the decay of uranium in soil and rocks. Radon can enter buildings through cracks in foundations, floors, walls, and openings around pipes. When radon and its radioactive decay products are inhaled, they can damage lung tissue and increase the risk of lung cancer. Poorly ventilated buildings may allow radon concentrations to accumulate. Radioactive substances also occur naturally in food and drinking water. Plants absorb radionuclides from soil, and these substances can subsequently enter animals and humans through the food chain. Potassium-40 is naturally present in many foods and in the human body. Small quantities of naturally occurring radionuclides may also be present in groundwater. Artificial sources contribute significantly to radiation exposure in modern society. Medical applications are among the most important artificial sources. X-rays, computed tomography (CT), fluoroscopy, and nuclear medicine procedures use ionizing radiation for diagnosis and treatment. Radiotherapy deliberately uses high-energy radiation to destroy cancer cells. When appropriately justified and controlled, medical radiation provides major health benefits; however, unnecessary or excessive exposure can increase health risks. Nuclear power plants are another source associated with radioactive materials. Nuclear reactors use controlled nuclear fission to generate energy. Under normal operating conditions, radiation exposure to the general population is kept very low through shielding, containment, monitoring, and regulatory controls. However, accidents involving nuclear facilities can release radioactive materials into the environment. Major nuclear accidents have demonstrated that radioactive contamination can spread through air, water, soil, vegetation, and food. Nuclear weapons testing and nuclear explosions can produce radioactive fallout. Radioactive particles released into the atmosphere may travel long distances before settling on land and water. Atmospheric nuclear testing in the past contributed to worldwide environmental contamination and increased human exposure to certain radionuclides. Industrial activities also use radioactive materials. Radioisotopes are employed in industrial