What is the increase of ionizing radiation that one receives from a coronal mass ejection or solar flare that is aimed directly at the Earth?
The amount of any radiation increase depends on location. If you are in a spacecraft outside the Earth’s magnetic field, the radiation doses can be quite large (as much as tens of sievert, 1 Sv = 100 rem; sievert and rem are units of radiation dose). If you are in a spacecraft, such as the Space Shuttle or International Space Station, the doses are lower (fractions of a sievert). Values depend on the altitude and inclination of the orbit and the amount of shielding provided by the spacecraft. In high-altitude aircraft (~65,000 ft), near the poles, doses from solar particle events are measurable, but not above limits for the general public. For most aircraft altitudes (below 45,000 ft), doses are negligible. A good source of information is the Proceedings of the 1998 Annual Meeting of the National Council on Radiation Protection and Measurements, which were published in the November 2000 issue of Health Physics.
