As a commercial airline pilot, Theresia Eberbach typically weighs several factors when deciding which trips to fly—the dates, destination and how long she’ll be away from home. Unlike most of her peers, Eberbach often has another variable to mull: How much radiation she’s willing to take.
Ionizing radiation is a permanent feature of the upper atmosphere, where the protection we take for granted on the surface is significantly thinner. At airlines’ cruising altitude, particles periodically ejected by the sun and cosmic radiation coursing through the universe are 100 times more potent than down below.
Still, the exposure for every extra-long trip across the globe is roughly equivalent to one X-ray. That is, except for two regions: The poles. The planet’s magnetic field helps to minimise radiation for most latitudes, but that shield tends to dissipate at extreme north and south. Airline employees are already the most vulnerable to workplace radiation, but the growing number of polar and long-haul routes may make the hazard worse. A flight from Germany to Southeast Asia can be just as long as one to the western US, but the risks can be very different given the latter goes “over the top” of the world.
“If I go to Los Angeles or San Francisco, it’s going to be the highest dosage in our network, whereas when I go to New Delhi or Singapore, it’s about a third of those doses,” said Eberbach, an Airbus A380 first officer for Deutsche Lufthansa who also serves as chairman of a radiation protection working group for Vereinigung Cockpit, or VC, the German pilots’ union.
Airline employees face more radiation exposure than radiology workers or nuclear power plant engineers, according to the National Council on Radiation Protection and Measurements. Such exposure is measured using the Sievert. A dose of 4 Sieverts or more at once is often fatal. A CT scan of your head is about 2 milliSieverts (mSv), or two-thousandths of a Sievert, roughly what you’d get going about your daily life for eight months.