What Are the Four Types of Radiation?

The four major types of radiation include alpha particles, beta particles, neutrons, and electromagnetic radiation. We are exposed to different levels of radiation in our everyday lives, including from healthcare (X-rays, CT scans, mammograms), air travel, building materials, cigarette smoking, cell phones, wearable technology, and more.

Radiation is energy that originates from a source and travels through space at the speed of light. Energy from radiation has both electric and magnetic fields associated with it and wave-like properties.

We are exposed to radiation on a daily basis but most of it is not sufficient to cause a problem.

Different types of radiation travel different distances and have different abilities to penetrate, depending on their mass and energy. Some types of radiation can have practical applications, such as in medicine. The four major types of radiation include:

1. Alpha particles

• The heaviest type of radiation particle, consisting of two protons and two neutrons
• Many naturally occurring radioactive materials in the earth, such as uranium and thorium, emit alpha particles
• These particles are very heavy and with a very large charge and do not travel very far
  • An alpha particle outside the body won't penetrate the surface of the skin, but if material that emits alpha particles is inhaled or ingested, sensitive lung tissue can be exposed
  • This is why high levels of radon are considered a problem in the home

  2. Beta particles

  • An electron not attached to an atom with a small mass and a negative charge
  • These particles can travel a little farther than alpha particles
  • They can get into the body but cannot go all the way through
  • Beta particles can be useful in medical imaging if released by a material injected into the body, such as in cancer therapy when radioactive material is injected into a tumor
  • Carbon-14, used in carbon-dating of fossils and other artifacts emits beta particles
  • Tritium, produced by cosmic radiation in the atmosphere and exists all around us, emits beta radiation
  • A particle with no charge that is present in the nucleus of an atom
  • Commonly seen when uranium atoms split (fission) in a nuclear reactor
    • Neutrons enable nuclear reactions used to generate power
    • They can only be stopped with large quantities of water or other materials made of very light atoms

    4. Electromagnetic radiation

    • There is no mass or charge to this type of radiation
    • Rays are like sunlight, but they have more energy
    • Used widely in medical treatments
      • Includes X-rays and gamma rays, which can penetrate through the body
      • Energy can range from very low, such as in dental X-rays, to very high levels such as in irradiators used to sterilize medical equipment

      What Are Common Sources of Radiation?

      There are a number of sources of radiation we encounter in our everyday lives.

      • Healthcare uses
        • To help diagnose, manage, or treat some health conditions
          • Computed tomography (CT) scans
          • Radiography and dental X-rays
          • Mammography
          • DEXA scans (bone densitometry)
          • Fluoroscopy
          • Nuclear medicine
          • Air travel
            • Cosmic radiation from space
            • Airport security screening
            • Those made of concrete, brick, sandstone, natural stone, gypsum, or granite contain naturally-occurring radioactive elements such as radium, uranium, and thorium which may emit low levels of radiation
            • Tobacco contains radioactive materials polonium-210 and lead-210
            • Uses radiation (RF) to send signals, which is different from other types of radiation (such as X-rays) that are known to be harmful
            • It is currently unknown if RF radiation from cell phones can cause health problems
            • Sunlight
            • Tanning beds
            • Mercury vapor lighting (often found in stadiums and school gyms)
            • Some halogen, fluorescent, and incandescent lights
            • Some types of lasers
            • Typically uses low-powered radiofrequency (RF) transmitters to send and receive data from smartphones or the Internet
            • RF transmitters emit radio waves, a type of non-ionizing radiation
            • From space: cosmic radiation
            • From earth: terrestrial radiation

            What Are the Health Effects of Radiation?

            Radiation can damage the DNA in our cells. However, as with many other toxins, radiation damage is dose dependent. We are exposed to low doses of radiation in our daily lives.

            Factors that can affect radiation exposure include:

            • Time
              • Limiting or minimizing exposure time reduces the dose
              • Exposure to a dose over a long period of time is less harmful than exposure to the same dose all at once
              • The dose of radiation decreases as you move farther away from the source
              • A dose to part of the body causes less harm than a dose to the entire body
              • Lead, concrete, or water barriers can provide protection from penetrating radiation and reduce or eliminate exposure
              • Children and young adults are more sensitive to the effects of radiation

              High doses of radiation may cause:

              • Acute Radiation Syndrome (ARS)
              • Cutaneous Radiation Injuries (CRI)
              • Cancer later in life
              • Harm to a fetus
              • Death