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Cosmic Radiation During Flights

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This page describes cosmic radiation and the reason our cosmic exposure increases when we fly in planes.

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Earth and its inhabitants are constantly showered by radiation from space, like a steady drizzle of rain. This shower of cosmic radiation is created by charged, “sub-atomic particles” (parts of atoms) that originate in our galaxy, other galaxies, and the sun. The particles interact with Earth’s atmosphere and magnetic field to create cosmic radiation.

The charged particles exhibit a wide range of energies and the rate at which cosmic rays bombard Earth depends on whether they are low- or high-energy. The vast majority of cosmic rays are low-energy. Although, high-energy cosmic particles constantly pass through and sometimes interact with our body, they are very rare and very difficult to detect.

About eight percent of our annual radiation exposure comes from outer space. The atmosphere shields us from cosmic radiation, and the more air that is between us and outer space, the more shielding we have. The closer we get to outer space, the more we are exposed to cosmic radiation. This holds true when we live at high altitudes or fly.

Our exposure to cosmic radiation partially depends on the elevation of where we live. For example, people who live in Denver, Colorado, which is more than 5,000 feet above sea level, are exposed to more cosmic radiation than people living in Chicago, Illinois, which is only about 700 feet above sea level. For the same reasons described above, we are exposed to higher levels of cosmic radiation when we fly on a commercial airplane.

The amount of cosmic radiation you are exposed to while flying depends on your altitude and latitude (distance from the Earth’s equator) and solar activity. For a typical cross-country flight in a commercial airplane, you are likely to receive 2 to 5 millirem (mrem) of radiation, less than half the radiation dose you receive from a chest x-ray. People in the United States receive an average of 360 mrem of radiation per year from natural and man-made radiation sources, which includes cosmic radiation exposure during commercial flights.

Who is protecting you

Federal Aviation Administration (FAA)

Solar events, like sun spots, can produce elevated radiation levels at high altitudes and/or latitudes. To prevent increased exposure to cosmic radiation, routine forecasts and alerts are sent through the FAA so that a flight traveling during a solar event can alter its flight plan by reducing altitude. The FAA has developed a computer software program for public use, entitled CARI-6, which provides an estimated equivalent radiation dose for flights.

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What you can do to protect yourself

There are no practical ways to shield yourself from cosmic radiation during a flight. You can reduce your exposure while flying by taking shorter flights at lower altitudes. This is often not practical, and the risks from cosmic radiation do not warrant changing your travel plans to reduce your exposure.

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Cosmic Rays
August 13, 2012. National Aeronautics and Space Administration.
This Web page offers more details on cosmic radiation.
How to Build a Cosmic Ray Cloud Chamber (PDF) (6pp, 3.5Mb) [about pdf format]
August 13, 2012. Fermi National Accelerator Laboratory.
This Web page shows you how to build a cloud chamber to capture the action of cosmic radiation.
Radiation Exposure During Commercial Airline Flights   exit EPA
August 13, 2012. Health Physics Society.
You can learn what several researchers have learned about radiation exposure during air travel.
Radiation and Air Carrier Crew Members exit EPA
August 13, 2012. Association of Flight Attendants.
You can read about airline flights and radiation exposure on the Web site. It focuses on exposure of airline crews.
Radiation Measurement
August 13. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention.
This page provides information on how radiation is measured and typical dose levels of radiation.
Radiobiology Research Team
August 13, 2012. U.S. Federal Aviation Administration.
On this page, you can find links to several articles about radiation and airline travel. One of the links leads to a computer program that calculates the dose of cosmic radiation received by an individual flying between any two airports in the world.

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