1. Radiation in the Workplace
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In this lesson, you will learn how to:
Explain what causes radiation.
Identify the three main types of radiation (radioactive decay) we may encounter in the workplace.
Rank the types of radiation by how far they can penetrate into the human body.
What Is Radiation?
Types of Radiation
References
DISCLAIMER: This presentation may contain material protected under copyright law. This material was obtained and used following a reasoned analysis of the Fair Use exemption for educators. This presentation may not be reproduced.

2. Knowledge Check 1: Question A
What Is Radiation?
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Watch this 4-minute video by the Canadian Nuclear Safety Commission to understand what causes radiation, then click the Knowledge Check 1 buttons below to test your understanding.
What Is Radiation?
Types of Radiation
Knowledge Check 1: Question A
References
Knowledge Check 1:
Question B

3. Knowledge Check 1: Question A
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What causes radioactive decay (radiation)? Click the box next to the best answer.
What Is Radiation?
The protons and neutrons in an atom’s nucleus are balanced.
Unstable atoms emit particles or energy until they become stable.
Elements are listed in the periodic table.
Knowledge Check 1: Question B

4. Knowledge Check 1: Question A – Feedback
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Try again. Return to the question or review the video. Hint: Radiation requires an unbalanced nucleus.
What Is Radiation?
Knowledge Check 1: Question A

5. Knowledge Check 1: Question A – Feedback
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Yes! Radiation is caused by unstable atoms, which emit particles or energy until they become stable. Continue to Question B or return to review the video.
What Is Radiation?
Knowledge Check 1: Question B

6. Knowledge Check 1: Question B
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Click the boxes to choose the three main types of radioactive decay (radiation) in the workplace:
What Is Radiation?
Neutron
Try again. Neutrons are particles in the nucleus of an atom.
Knowledge Check 1: Question A
Gamma
Yes! Gamma rays are emitted by a decaying atom.
Alpha
Yes! Alpha particles are emitted by a decaying atom.
Proton
Try again. Protons are particles in the nucleus of an atom.
Beta
Yes! Beta particles are emitted by a decaying atom.

7. Types of Radiation in the Workplace
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The three main types of radiation of concern in the workplace are alpha particles, beta particles, and gamma rays. Scientists who discovered them named them after the first 3 letters of the Greek alphabet: α (alpha), β (beta), and γ (gamma). Click the buttons below to learn more about each type of radiation. Click Compare to compare their ability to penetrate the human body. When you are ready, complete Knowledge Check 2.
What Is Radiation?
Types of Radiation
References
Alpha Particles
Beta Particles
Gamma Rays
Compare
Knowledge Check 2

8. Alpha Particles (α)
Types of Radiation
Alpha particles are small chunks ejected from the nucleus of an unstable atom. They consist of two protons and two neutrons.
Alpha particles move only 2–3 inches in air before the air molecules stop them.
Click the alpha particle to the right to see how far it can penetrate into a human body.
Beta Particles + α +
Gamma Rays
Compare
Alpha particles cannot penetrate the top layer of dead cells on our skin. Clothing or a piece of paper can also stop them.
Alpha particles become dangerous when we inhale or ingest an alpha-emitting substance (through contaminated food or drink). Inside our body, they can damage tissues. Alpha-emitting substances include radon and uranium.
Knowledge Check 2

9. Beta Particles (β)
Types of Radiation
Beta particles are electrons that have been ejected from an unstable atom. Beta particles move very quickly. They can go several feet before stopped by air molecules. Click the beta particle to the right to see how far it can penetrate into a human body.
Alpha Particles - β -
Gamma Rays
Compare
Beta particles can penetrate a small distance into the flesh under our skin. They can be stopped by a thin piece of metal (such as aluminum), ¼ inch of Plexiglas®, several layers of clothing, or the soles of work boots.
Beta particles become dangerous when we inhale or ingest a beta-emitting substance (through contaminated food or drink). Inside our body, their quick movement can damage tissues. Beta-emitting substances include tritium, strontium-90, and carbon-14.
Knowledge Check 2

10. Gamma Rays (γ)
Types of Radiation
Gamma rays are waves of electromagnetic radiation emitted during the decay of an unstable nucleus. They consist of pure energy (high-energy photons). Gamma rays can go many feet before stopped by the molecules in the air. Click the gamma ray to the right to see how far it can penetrate into a human body. γ
Lead
Alpha Particles
Beta Particles
Compare
Gamma rays can penetrate far into the human body, or even go through it. They can also penetrate clothes, walls, and may kinds of metal. They can be stopped by a thick piece of lead or other dense materials.
Gamma rays can damage our cells in large doses. Sources of gamma rays include nuclear power reactors, medical imaging equipment, and the universe itself. Most countries have laws to limit the amount of radiation nuclear power and medical workers can be exposed to.
Knowledge Check 2

11. Compare Radioactive Penetration
Types of Radiation
Click each of the types of radiation below to compare how far they can penetrate into a human body. Which type is most penetrating? Which type is least penetrating?
Review the types of radiation or continue to Knowledge Check 2 when you are ready.
Alpha Particles
Beta Particles
Lead + α - β
Gamma Rays γ + -
Knowledge Check 2

12. Knowledge Check 2
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This knowledge check consists of two questions. Click on each question below.
What Is Radiation?
Knowledge Check 2: Question A
Knowledge Check 2: Question B
Types of Radiation
References

13. Knowledge Check 2: Question A
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Which of these sequences ranks the three types of radiation in order from least penetrating to most penetrating? Click the box with your choice:
Types of Radiation
Try again. Gamma rays can only be stopped by thick lead or other dense substances.
Gamma, Beta, Alpha
Knowledge Check 2: Question B
Try again. Alpha and beta particles are less penetrating than gamma rays.
Alpha, Gamma, Beta
Yes! Alpha particles are least penetrating because they can be stopped by skin. Beta particles can only penetrate a short distance under the skin. Gamma rays can pass through the whole body.
Alpha, Beta, Gamma

14. Knowledge Check 2: Question B
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Which two types of radiation are primarily dangerous when substances that emit them are inhaled or ingested? Click the two boxes with your choices:
Types of Radiation
Yes! Alpha particles cannot penetrate the skin from outside. They damage the body when alpha-emitting substances like radon or uranium are inhaled or ingested.
Alpha
Knowledge Check 2: Question A
Yes! Beta particles cannot penetrate far into the body and can be stopped by thick clothing or sheets of metal or Plexiglas. These particles damage the body when beta-emitting substances like tritium or strontium-90 are inhaled or ingested.
Beta
Gamma
Try again. Gamma rays can pass completely through the body on their own without ingestion of gamma-emitting substances. Damage to body tissues primarily occurs from large or prolonged exposure.

15. References Image Credits: Acknowledgements: Home What Is Radiation?
The technical content of this lesson is derived from the following sources: Canadian Nuclear Safety Commission. (2014). What Is Radiation? [YouTube video]. Retrieved from Health Physics Society. (2016). What Types of Radiation Are There? Retrieved from pes.html National Aeronautics and Space Administration, Goddard Space Flight Center. (2010). Processes that Create Cosmic Gamma Rays. Retrieved from a_generation.html SC&A, Inc. (2017). NORM/TENORM Awareness – U.S. Version [online course]. Retrieved from
Image Credits:
atom: gerault, Pixabay, CC0
hand: Clker-Free-Vector-Images, Pixabay, CC0
All other graphics © 2017 Anne M. Brophy
Acknowledgements:
Thanks to Patrick Kelly, Vice President and Senior Project Manager, SC&A, Inc., for answering questions about the technical content of this lesson.
What Is Radiation?
Types of Radiation
References
DISCLAIMER: This presentation may contain material protected under copyright law. This material was obtained and used following a reasoned analysis of the Fair Use exemption for educators. This presentation may not be reproduced.