Timothy J. Jorgensen, Director of the Health Physics and Radiation Protection Graduate Program and Associate Professor of Radiation Medicine, Georgetown University - You might guess that a frequent flyer’s radiation dose is coming from the airport security checkpoints, with their whole-body scanners and baggage x-ray machines, but you’d be wrong. The radiation doses to passengers from these security procedures are trivial. The major source of radiation exposure from air travel comes from the flight itself. Most people do not fly 370,000 miles (equal to 150 flights from Los Angeles to New York) within their lifetimes. So for the average flyer, the increased risk is far less than 0.01 percent.