Ionizing radiation presents a flow of various micro particles or electromagnetic fields, which have an ability to ionize a substance. In everyday life, ionizing radiation denotes penetrating radiation – a flow of gamma rays and particles (alpha, beta, neutrons).
Radiation is classified as ionizing and non-ionizing. Ionizing radiation consists of swift atomic, subatomic particles and photons having the energy enough to produce significant ionization of a substance (Alpha, beta, neutrons). The spontaneous disintegration of atoms is called radioactivity, and the excess energy emitted is a form of ionizing radiation.
Non-ionizing radiation is any kind of radiation in the electromagnetic spectrum that does not have enough energy to remove an electron from an atom and turn it into an ion. Non-ionizing radiation refers to electromagnetic waves, ranging from radio waves, though the visible light spectrum, and up through to gamma waves.
The image above shows where ionizing radiation is located in the electromagnetic spectrum
Types of Ionizing Radiation
Ionizing radiation presents a flow of various micro particles or electromagnetic fields, which have an ability to ionize a substance. In everyday life, ionizing radiation denotes penetrating radiation – a flow of gamma rays and particles (alpha, beta, neutrons). 
Alpha radiation – is a flow of He nuclei which results from alpha decay of the elements nuclei. Alpha radiation has high ionizing but low penetrating power. Human body can be protected from external alpha-particles flow by outerwear, rubber gloves, flu mask, even paper sheet. However, if alpha-particles sources penetrate a human body with air, water or food, it is very dangerous.
Beta radiation – is a flow of electrons or positrons, which results from beta nuclei decay. Beta radiation has lower ionizing but higher penetrating power than that of alpha. Any shelter may serve a protection here. Beta particles can easily penetrate human skin and cause tissue damage and burns.
X-rays and Gamma radiation – electromagnetic radiation, which comes together with nuclear transformations. Gamma rays are photons that come from the nucleus of the atom. Both types of ionizing radiation can pass through the human body if they have enough energy. It appears extremely difficult to protect oneself from both X-rays and gamma-rays. Gamma rays intensity may be reduced two times with steel (2,8 сm thick), concrete (10 сm), soil (14 сm), wood (30 сm).
Neutron radiation denotes a flow of neutrons, i.e. heavy particles forming a constituent part of a nucleus. To protect oneself from this type or radiation one may use protective shelter, radiation protective covers, specially equipped basement or cellar. All kinds of barriers from polymers, polyethylene and even water appear efficient to protect a person from harmful radiation influence.