Cosmic Radiation and the Frequent Flyer

 
 
Ionizing Radiation
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Cosmic Radiation

 
  :: Table of contents
  1. Exposure to flight crew and frequent flyers
  2. Safety Standards for Radiation Dose Limits
 
Cosmic radiation image
Exposure to flight crew and frequent flyers

Cosmic radiation contributes about 13% of the natural background radiation level. It is believed to come from Milky Way galaxy but its’ origin is unclear. Cosmic radiation consists primarily of charged and neutral particles (protons, alpha particles, heavier ions, and electrons) and secondary particles generated by interaction of cosmic radiation with atmosphere’s air (ions, neutrons, gamma rays, electrons, etc). Along with solar radiation it constantly bombards Earth’s atmosphere.

The Earth’s magnetic field deflects many charged particles that would otherwise reach ground level but at jet aircraft attitudes cosmic radiation can contribute significantly to doses accumulated over hundreds flight-hours by flight crew and frequent flyers.

Flight crew is now recognized as occupationally exposed to radiation professional category and radiation protection limits for flight crew are similar to those in nuclear workers.

Short-haul vs. Long-haul

Short-haul flights are flown at lower altitudes than long-haul flights. Consequently, there is more radiation shielding provided by atmospheric air at lower altitudes and lower dose received from cosmic radiation. The latitude of the flight route also makes a difference in the level of cosmic radiation exposure. If two same-distance flights are flown at different geographic latitudes but at the same altitude, the cosmic radiation level on the lower-latitude flight will be usually lower of the two because of the greater shielding factor provided by earth's magnetic filed. This shielding is maximum at the equator and gradually decreases to zero at the south and north poles.

For example, in 1958-200, at an altitude of 10,000 m the average galactic cosmic radiation level over Reykjavik, Iceland (64°N, 22°W), was approximately twice that over Lima, Peru (12°S, 77°W)

WHO is in the process of developing a Fact Sheet on Cosmic Radiation and Exposure, as well as producing occupational safety information for civil aviation workers.

 
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  :: Table of contents
  1. Exposure to flight crew and frequent flyers
  2. Safety Standards for Radiation Dose Limits
 
Safety Standards for Radiation Dose Limits

Public exposure to ionizing radiation, including cosmic radiation, is regulated by safety standards developed to protect the general public and occupationally exposed workers from the risks arising from ionizing radiation.

Detailed information may be found in the Safety Series publication of the International Atomic Energy Agency “International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources”. For European countries, the most recent version of such standards is contained in Council Directive 96/29/Euratom of 13 May 1996 laying down basic safety standards for the protection of the health of workers and the general public.

Annual exposure dose limit for a member of general public is 1 milli-Sieverts (mSv) and occupational limits is 5 mSv. Exposure dose from cosmic radiation at flight altitudes is usually not higher than 0.005 mSv per hour. Rough estimates show that it will take a minimum a 200 flight hours to approach annual dose limit for general public.

ADDITIONAL INFORMATION

About cosmic radiation and its health effects may be found at the following web sites:

- Civil Aerospace Medical Institute of the U.S. Federal Aviation Administration:
Aeromedical Research
- Civil Aerospace Medical Institute of the U.S. Federal Aviation Administration: Training Questions
Training Questions and Answers.
- Civil Aerospace Medical Institute of the U.S. Federal Aviation Administration: Reports
FAA report on Galactic Cosmic Radiation Exposure of Pregnant Aircrew Members and other reports.
- Civil Aerospace Medical Institute of the U.S. Federal Aviation Administration: On-line dose calculator
FAA’s on-line dose calculator will tell you what radiation dose range you received during your flight:
- Health Physics Society
"Ask the Experts" FAQ section on Aircraft Radiation Exposure
- UNCEAR
United Nations Scientific Committee on the Effects of Atomic Radiation UNSCEAR 2000 Report to the General Assembly, with scientific annexes
- Canadian Radiation Protect Bureau
Cosmic Radiation Exposure and Air travel
- Aviation Health Institute (UK)
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