Airplane Radiation: A Growing Concern
Conventional wisdom says that airplane radiation is a moderate risk factor due to the fact that at higher altitudes, there is less protection from cosmic rays. Airplane radiation was an acceptable risk for occasional passengers and even frequent fliers.
Lately however, stratospheric radioactivity levels have risen, due to airborne dust particles of Plutonium-239, Cesium-137 and Uranium are raising new concerns about airplane radiation. The video below documents Geiger counter readings for 45 minutes of flight time on a trip from San Francisco to Honolulu. The video itself is quite boring, but it does indicate airplane radiation levels peak at 0.256mR/h which is more than a year’s allotment per hour. Means that on a typical 5-hour flight a person might receive 5 times the yearly safe level of background radiation. If it is a round trip, that would be 10 times the yearly safe level. If a person makes a total of 2 5-hour round trip flights with these measurements, they will have absorbed the maximum allowable yearly dose for radiation workers. So what does this mean?
Airplane Radiation & Stochastic Effects
To really understand the impact of airplane radiation, one needs to understand what is meant by the term, “stochastic effects.” Stochastic is a fancy word for effects where chance plays a role. Rather than saying that airplane radiation definitely will or will not cause cancer, given the somewhat random variables involved with atomic decay, it is more accurate to state cancer risk in terms of odds, sort of like the concept of a “dead man’s hand” in cards. (Legend has it that “two black Aces, two black eights and the Queen of clubs” are “a dead man’s hand” and a predictor of imminent death for the person holding the cards). Odds are 1 in 2,598,960 that a person would be dealt that hand. Pretty slim odds. The flip side is that the more poker a person plays, the more likely they will be dealt that hand.
Airplane Radiation Risks For Frequent Fliers
It turns out that airplane radiation risks do indeed add up. Statistically, airline pilots and stewardesses turn out to have a higher incidence of certain cancers. Pilots are more likely to get colon, rectal, prostate and brain cancers, while flight attendants are twice as likely to suffer breast cancer. Unfortunately, the figures have not been revised in light of the increased levels of airplane radiation after the Fukushima Daiichi disaster. The latency period for cancer may be 5 to 20 years. Traditionally, the risks for the casual flyer have not been great, but with increased levels of radioactive particles this may no longer be true.
The following clinical study may shed some light on airplane radiation risks. A carefully conducted study showed a 1.3% rise in cancer mortality among radiation workers: “A 15-Country collaborative cohort study was conducted to provide direct estimates of cancer risk following protracted low doses of ionizing radiation. Analyses included 407,391 nuclear industry workers monitored individually for external radiation and 5.2 million person-years of follow-up. A significant association was seen between radiation dose and all-cause mortality [excess relative risk (ERR) 0.42 per Sv, 90% CI 0.07, 0.79; 18,993 deaths]. This was mainly attributable to a dose-related increase in all cancer mortality (ERR/Sv 0.97, 90% CI 0.28, 1.77; 5233 deaths).” http://www.ncbi.nlm.nih.gov/pubmed/17388693
So simply as a ballpark figure with regard to airplane radiation, if we assume that each round trip flight exposes a person to about half the yearly allowable dose for radiation workers, then one might expect that 30 flights would be approximately equivalent to the 15 years examined in the study, possibly resulting in a 1.3% increase in cancer risk. Based on that estimate, the casual air traveler still faces little risk, but the frequent flier faces a real risk for exposure.
One might imagine a business traveler making a round-trip flight every two weeks for 5 years. This would result in 4 times the exposure that the radiation workers faced in 15 years and would likely make airplane radiation a cause for concern.
Mitigating Airplane Radiation
It turns out that the primary risk for airplane radiation is one of inhaling microscopic radioactive dust particles that are pumped in to freshen the cabin air. Although this air is filtered, many of the particles are too small and pass right through. The good news is that the risks can be solved through the use of a HEPA respirator mask.