Radiation is a fundamental fact of our natural world. For a definition of what radiation is, see our introduction to nuclear terms. Radiation is generated by a number of sources in our natural environment. Cosmic rays from space strike the upper atmosphere of the earth creating a rain of high energy particles that strike the surface of the earth, including us. Radioactive potassium exists in our food and in our bodies as well as all throughout the environment in general. Radon (which is radioactive) can seep up from the ground into our basements if they are not properly sealed. All of these things contribute to our radiation dose.
Average radiation exposure for humans
The estimated yearly radioactive dosage to humans in the world is around 2.2 mSv per year1 . See our radiation terms for an explanation of what dose and sievert mean. There are places in the world where the dosage is much higher, such as in Ramsar, Iran where dose to the public has been estimated as high as 260 mSv per year2 . No adverse effects have been observed in the populations who have lived in such high radiation areas their entire lives1 .
Our everyday choices affect our dose
Furthermore, some common actions we voluntarily perform substantially increase our exposure to radiation. People undergoing medical diagnostic procedures such as x-rays and MRIs absorb additional radiation, as well as those who fly in airplanes. The higher and further the flight, the more additional cosmic rays passengers are exposed to.
We are not saying this to scare you, or to trivialize the potential danger that high levels of radiation may pose, but to give the reader a better understanding of what radiation is and what role it plays in their lives. Little, unconscious actions we perform expose us to radiation and other additional risks. Making a trip to the store on a day with a particularly high UV-index exposes us to additional ultraviolet radiation. A portion of the sun’s light is a form of radiation which increases our risk of developing skin cancer, as well as increasing our body’s vitamin D production. Obviously there are health benefits as well as risks to sun exposure. Just as driving longer distances per day increases the changes of getting in a car accident, being in the sun more increases the chances of developing skin cancer. Similar dangers exist for most forms of chemicals used by our civilization.
Radon is a well known radioactive danger. It can seep up from the ground into our basements if and can deliver doses to humans as well. Radon is a danger underestimated by most people. The United States Environmental Protection Agency estimates that radon is the second leading cause of lung cancer, after smoking3 . It is estimated to be responsible for about 21,000 deaths per year in the United States.
What are the legal limits on radiation exposure?
Nuclear regulations in Canada and the United States limit the maximal additional yearly dose (above the background level) to a member of the general public to 1mSv (millisieverts) per year4 . We can compare this to the average dose per year per human of 2.2 mSv from the environment. Thus the maximum legally allowed dosage would add about 30% to the background radiation on average. In an extreme case, such as a high-radiation area like Ramsar, the estimated yearly dose due to the environment is as high as 260 mSv per year. We can see that the same legal limit would amount to less than half of one percent of all radiation delivered in such a case.
Human-made radiation sources
Human-made sources of radiation have increased the average dose of humans around the world by about 20%, with most of this increase coming from radiation therapy applied in a medical setting. Only an estimated 0.1% is due to nuclear power, nuclear weapons tests, and the Chernobyl incident1 . For a visual breakdown of some estimates of doses from various sources, see this image from world-nuclear.org that breaks down radioactive dose according to origin.
Coal power is greater radioactive danger
Coal power is responsible for more radiation pollution than nuclear power5 . While nuclear waste is highly radioactive, it is very carefully shielded. The radiation emission of nuclear waste strikes the waste container and is absorbed, turning most of the energy into heat. On the other hand, fly ash from coal plants is much more exposed to our air and water systems. There are radioactive elements in coal fly ash which then get into our air and water and deliver radioactive doses. For a good example of such an event, see the Coal Fly Ash Slurry Spill, overseen by the Tennessee Valley Authority. Estimates have been made that coal power emits at least several times as much radiation as nuclear power, and up to thousands of times higher5 .
Answer: nuclear power emits very little radiation
Nuclear power is legally obligated to keep its radioactive emissions incredibly low. Even people who live close to nuclear power plants will receive from them only a fraction of the dose that they receive naturally from their environment. Human-made sources account for about 20% of the dose to humans, with nuclear power composing less than 1% of the total dose. Coal is responsible for a larger portion of radioactive dose than nuclear is. This is a point missed by most people involved in the world discussion about energy sources.
This article is part of our nuclear myth and fact project.
- Jaworoski, Z. Radiation Risk and Ethics. American Institute of Physics. Physics Today. (1999). [↩] [↩] [↩]
- Ghiassi-nejad, M.; Mortazavi, S. M. J.; Cameron, J. R.; Niroomand-rad, A.; Karam, P. A. Very High Background Radiation Areas of Ramsar, Iran: Preliminary Biological Studies. Health Physics 82,1, 87-93 (2002). [↩]
- United States Environmental Protection Agency. Radon Health Risks. [↩]
- Radiation Dose Limit. McGill University Radiation Safety Policy Manual. [↩]
- Coal Ash is More Radioactive than Nuclear Waste. Scientific American. (2007). [↩] [↩]
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