Phoenix2006 Blog
Re: Radiation and Health
Posted By: msung, McMaster Science on Thursday, June 08, 2006
Hi Samantha,
You asked a really good question. It is true that at higher latitudes one would experience more cosmic radiation. This is because cosmic radiation (especially at higher altitudes) are mostly composed of charged particles, like protons and electron and the earth's magnetic field is stronger near the equater than at the poles. This results in more cosmic particles being deflected at the equater than at the polar regions.
So back to pilots. So we've established that depending on what latitude you are flying at, you may accumulate more or less dose. However it is difficult to say that a pilot flying over greenland would neccisarily be exposed to more radiation than another pilot flying across the pacific ocean. This is because there are a number of factors which can affect one's exposure from flying significantly.
Some factors to consider are: 1) The altitude that the plane reaches. This is because the earths atmosphere helps to shield/or filter out the high energy particles making up cosmic radiation and so the higher you go into the atmosphere the less shielding effect you would get. 2)
The sun's magnetic field can also deflect cosmic radiation away from the earth, so depending on the stage of the solar cycle you will have varying amounts of cosmic radiation. For instance during a solar minimum (least amount of solar activity) the sun's magnetic field is the least effective at deflecting cosmic radiation from the earth so, more cosmic radiation exposure results. 3) Occasionally solar flare ups can occur, where the sun emits a burst of high energy particles which will in turn increase the amount of cosmic radiation reaching the earth's atmosphere.
Finally, while there have been studies published on trying to make correlations between cancer and pilots and/or flight attendants. Different studies show different results. While studies suggest increases in incidences of certain types of cancer (ie. excess breast cancer amoung females working for a Finnish airline) other studies find no significant correlation between airline flight crew and cancer incidence.
I personally don't know which side of the issue I stand on as there is evidence going both ways. However I will lastly just mention this. The average flight personnel will accumulate 2-5 milliSeiverts of radiation in a given year while the recommended annual limit for occupationally exposed workers is 20 milliSeiverts (ICRP recommendations -- International Commission on Radiological Protection). So to me, it doesn't sound like an overly dangerous exposure especially since you will accumulate an average dose of 5 milliSeiverts from a chest x-ray.
Melissa Sung
Radiation and Health
Posted By: samanthal, CCI on Friday, May 26, 2006
If pilots are exposed to excess radiation, especially around the polar regions, would it be possible that some pilots have lower risks of developing tumors?
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