Airline Passengers May Face Radiation Risk

Crowded planes, lost luggage and a severe lack of elbow room likely rank high among most travelers' worries about flying. Terrestrial gamma-ray flashes (TGFs), however, probably do not.

In a fraction of a second, these gamma-ray flashes produced by lightning could expose airline travelers to 30 times more radiation than they should receive in an entire year.

Professor Joseph Dwyer of the Florida Institute of Technology led a study analyzing the mysterious radioactive anomalies that appear to originate inside of thunderstorms. Dwyer investigated whether these flashes could expose airline passengers and crew to high gamma-ray doses.

Originally discovered in 1994 by NASA's orbiting Compton Gamma Ray Observatory, TGFs most likely occur during lightning flashes, which generate electric fields.

These fields, Dwyer explained, accelerate a large number of electrons up to nearly the speed of light. The high-energy electrons then collide with atoms in the air and emit gamma rays that can be observed from space.

Researchers are unsure how often TGFs occur in Earth's atmosphere. In the 1990s, NASA's observatory recorded about 70 TGFs over eight years. Meanwhile, commercial aircraft endure, on average, one to two lightning strikes a year.

Dwyer and his team analyzed orbital recordings of TGFs. On the ground, they also observed both naturally occurring lightning and artificial lightning summoned through the use of wire-guided rockets.

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TGFs typically occur at the same altitude as commercial airline flight paths, leading Dwyer and his team to explore the risk to human crews. Based on their findings and current scientific understanding of thunderstorms and lightning, the researchers suggested that airline passengers and crew occasionally could fly into harm's way.

"One-tenth of a rem per year is about as much as anyone should get," Dwyer told Discovery News. "It is feasible that someone inside an aircraft, who is in the wrong place at the wrong time, could receive 30 times more than that (dose) in just 0.0002 seconds."

Despite the high levels of radiation involved, Dwyer insists that there's no call to panic.

"At this time, more research is needed before we say that people should worry," Dwyer said. "For instance, I still feel comfortable flying with my family."

That's a sentiment shared by Professor Chathan Cooke of the Massachusetts Institute of Technology's High Voltage Research Lab, who told Discovery News that he is critical of both the study and its media coverage.

Cooke said he wasn't convinced that the evidence from this initial study warranted TGFs being raised as a public issue. He also said that talk of gamma radiation will only alarm and confuse people.

Dwyer's study is set to appear in the Journal of Geophysical Research, Atmospheres.

Robert Lamb is a writer for HowStuffWorks.com.