Day 14: Radiation on a Plane

When I was replacing my dosimetry badge after leaving the HZB nuclear reactor in Wannsee, I asked Robert if he had ever had to take time off due to exposure to radiation. His replied that pilots, and even frequent flyers, are exposed to significantly larger doses than those working in this reactor. In fact, he said, pilots have a younger retiring age than most professions for this very reason.

I am now sitting in the back of a 747 somewhere over China, trying to keep from elbowing my neighbours as I type. Engrossed in a film - some science fiction epic - the lady beside me is unaware that she is being bombarded with unusually high levels of radiation.

The physics questions for today are: Why are we exposed to more radiation when we are flying than when we are on the ground? What is the nature of this radiation? And what is the source?