Cosmic radiation

Space is a harsh environment. We’re all familiar with the big risks from television – asteroids, solar flares, lack of air, extreme temperatures, and the occasional testy alien ships. What we don’t think about quite as much is the radiation. With trips to the Moon and Mars, in the planning stages, we are once again about to send people into that harsh universe. In addition to the engineering, logistics, and everything else that goes into such trips, NASA is looking at revising the limits for radiation exposure its astronauts can receive. 
Cosmic rays are the largest source of radiation exposure associated with flying, and it may have health impacts on flight crews. A new study suggests that the risk of cancer may be increased, but "may" is the operative word. As for the flying public, there should be no concern.