Radiation is energy emitted from a source, such as heat, sunlight, microwaves, x-rays, and gamma rays. Ionizing radiation is a type of radiation that has enough energy to remove electrons from atoms, causing them to become charged or ionized. Not all electromagnetic radiation is ionizing; only the high-frequency portion of the spectrum, which includes x-rays and gamma rays, is considered ionizing. Particle radiation is another form of ionizing radiation and consists of atomic or subatomic particles like electrons and protons.
Gamma and x-rays are indirectly ionizing radiation because they are electrically neutral and do not interact with atomic electrons through coulombic forces. The amount of energy imparted to the human body from ionizing radiation is what can cause harm to health. To measure this, the international unit of measurement (SI) for an absorbed dose is gray (Gy), which is defined as 1 joule of energy deposited in 1 kilogram of mass. The old unit of measurement for this is rad, which means absorbed dose of radiation. A gray equals 100 rads. Ionizing radiation is present in the environment in air, water, food, soil, and living organisms.
In fact, a large portion of the average annual dose of radiation people receive comes from natural environmental sources. Each person is exposed to an average of 2.4 mSv per year of ionizing radiation from natural sources. In some areas of the world, the dose of natural radiation can be 5 to 10 times higher for a large number of people. Ionizing radiation has a flow of several microparticles or electromagnetic fields that have the ability to ionize a substance. In everyday life, ionizing radiation refers to penetrating radiation that consists of gamma rays and particles like alpha, beta, and neutrons.
Neutrons are generally unable to ionize an atom directly due to their lack of charge; most commonly neutrons ionize indirectly since they are absorbed into a stable atom, making it unstable and more likely to emit ionizing radiation.
