Boeing in air
"Cosmic radiation is effectively absorbed by the atmosphere and is also affected by the earth's magnetic field. The effect on the body will depend on the latitude and altitude at which the individual is flying and also the length of time in the air."- from British Airways
Coming off of two flights this past week I couldn't help but think about the cosmic radiation that I was absorbing. From what I have learned it doesn't actually seem to be dangerous, but it is something I didn't know about until recently.
Here's some handy info from the Canadian government in case you want to learn more.
Wikipedia's take on the Cosmic Ray.