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| Fig. 1: Solar flare captured by NASA in March of 2014. (Courtesy of NASA. Source: Wikimedia Commons) |
Apparently full body scans aren't the only sources of radiation to be worried about during air travel. While preflight body scans result in very low levels of radiation exposure, actual flight time may also result in similar exposure, if not more. However, nowadays with an increasingly connected and busy world, the accumulation of air travel is becoming a real concern. Current levels of radiation exposure for over 100million people globally are above 1 mSv a year on average. In more extreme cases, people can experience levels above 5 mSv. However, these effects are only experienced by about 2 million people. [1] Comparing this to business employees, pilots, and seasoned travelers begs the question as to how much are they are additionally affected by radiation and the risks that are associated with it. This thought is what also inspired the International Commission on Radiological Protection (ICRP) to take steps towards measuring the exposure. Eventually in 1990, they concluded that cosmic ray exposure of high altitude flights be an important factor when considering occupational hazards in the flight industry. [2]
There are four main factors that impact the exposure of cosmic radiation during plane flights: altitude, latitude, solar activity, and time. [3] The atmosphere is supposed to protect the Earth from incoming radiation by deflecting rays back into space. However, as the altitude increases, the air outside gets thinner. With fewer particles per volume of space, the radiation strength increases because there are fewer molecules present to deflect those rays. Also, the higher the flight latitude is above or below the equator, the more radiation. [2] This is a result of the geomagnetic effect impacting lower level cosmic rays from reaching different layers within the atmosphere. The magnetic field is also impacted by the varying solar winds due to solar flare-ups, directly changing the density of the radiation, which can be seen in Fig. 1. Lastly, of course the longer you are in the air the longer you are exposed to the cosmic rays. [1]
Now that we have a better understanding of where this solar radiation is coming from, it is next important to discuss its effects and just how much we should be concerned at the risk it poses to flyers. Research studies show that internationally the average is only about 1𝜇Sv each year from flying. However, for those that are more frequently spending their time in the air, the risk increases to about an additional 1 mSv. This translates into less than a 1% difference of what people typically receive on the ground, meaning that the risk, while present, is not as pressing as one might think. [1] Additionally, we know that an average flight from coast to coast in the United States results in less than a 20𝜇Sv dose of radiation in flight. If we do a quick calculation and assume that someone is flying back and forth across the country for an entire year nonstop and that a single flight is about 6 hours, we get about 3mSv of radiation exposure, which is between normal and extreme levels globally. [4] While this may not be the most extreme case out there, it is still important for us to take into consideration this higher risk for pilots and frequent fliers, also how future flights and aviation advances might influence it. [3]
© Kiana Pancino. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] A. Bouville and W. M. Lowder, "Human Population Exposure to Cosmic Radiation," Radiat. Prot. Dosim. 24, 293 (1988).
[2] P. Goldhagen, "Overview Of Aircraft Radiation Exposure And Recent Er-2 Measurements," Health Phys. 79, 526 (2000).
[3] F. Spurný, K. Kudela, and T. Dachev, "Airplane Radiation Dose Decrease During a Strong Forbush Decrease," Space Weather 2, S05001 (2004).
[4] I. L. Getley et al., "Radiation Dose Along North American Transcontinental Flight Paths During Quiescent and Disturbed Geomagnetic Conditions," Space Weather 3, S01004 (2005).
