Airplane Passengers May Risk Radiation Exposure When Passing Through Storm Clouds - Brandon Wenerd
December 10, 2009Passengers on planes flying near or through lightning storms could be exposed to harmful levels of radiation, according to a study in an upcoming issue of the Journal of Geophysical Research - Atmospheres. Lightning discharges, or a related phenomena known as terrestrial gamma-ray flashes, could jolt airline passengers with a level of radiation equivalent to 400 chest X-rays, reports LiveScience.com, which published a summary of the study on December 9th.
Researchers stated that the likelihood of airplane passengers and crews encountering this type of lightning event is very small.
The study was conducted by estimating radiation levels based on satellite and ground observations of X-rays and gamma rays. Terrestrial gamma-ray flashes—or TGFs—are mysterious phenomena that are believed to originate at the same flying altitudes as airliners. For the study, satellites were used to collect data on TGFs, which scientists believe are produced in the electric fields above the thunderstorms.
According to LiveScience.com, researchers also measured the levels of X-rays and gamma rays in natural lightning on the ground, as well as in artificial lightning triggered by wire-trailing rockets fired into storm clouds. Using computer models to estimate the levels of radiation produced within or near thunderclouds during a lightning storm, researchers concluded that the amount of radiation within immediate proximity to these lightning events could be high enough to be considered a "biologically significant level." The dosage measured by the scientists is considered to be the maximum amount of radiation a single person can safely receive over the course of a lifetime.
The only way airline passengers would be exposed to this high level of radiation is if their plane happens to be near the origin of a lightning discharge or a gamma-ray flash. According to the report, these types of radiation bursts are extremely brief, and scientists are not sure how often, if ever, this type of exposure occurs.
In the meantime, airline passengers are always exposed to slightly elevated levels of radiation from cosmic rays that blast the Earth's upper atmosphere, but typically never make it to the Earth's surface.
According to Joe Dwyer, a professor of physics and space sciences at Florida Tech, commercial airplanes are struck by lightning once or twice a year.
"What we don't know is how often planes happen to be in just the right place or right time to receive a high radiation dose. We believe it is very rare, but more research is needed to answer the question definitively," Dwyer told LiveScience.com.
Martin Uman, another author of the study, tells LiveScience that airline pilots typically try to avoid flying through lightning storms. Uman suggests there should be more scientific inquiry into the phenomena, recommending that the Federal Aviation Administration consider placing detectors aboard planes in order to measure the frequency of radiation bursts
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