Ionizing Radiation in Earth\u2019s Atmosphere and in Space Near Earth

Civil Aerospace Medical Institute2011PDFTech ReportFriedberg, WallaceCopeland, KyleCivil Aerospace Medical InstituteUnited States. Office of Aerospace MedicineUnited States. Office of Aerospace MedicineUnited StatesIonizing radiationCosmic raysOuter spaceAstronomical phenomenaRadiation hazardsAirspace (Aeronautics)Ionizing radiation, Cosmic radiation, Radioactive contamination, Space weather, Geomagnetism, Radiation exposure limits, Flight doses, Radiation health risksDOT/FAA/AM-11/9The Civil Aerospace Medical Institute of the FAA is charged with identifying health hazards in air travel and incommercial human space travel. This report addresses one of these hazards \u2013 ionizing radiation.Ionizing radiation is a subatomic particle of matter or packet of energy (photon) with sufficient energy to eject anorbital electron from an atom. Charged subatomic particles from exploding stars (supernovae) are a constantsource of ionizing radiation in the atmosphere and in space. In space another constant source of ionizingradiation is the solar wind from the Sun. The solar wind consists mostly of electrons and protons with energiesbetween 10 and 100 keV. The Sun undergoes an approximately 11-year cycle of rise and decline in activity andduring its active phase there is an increased emission of the solar wind and occasional eruptions of high-energyparticles (coronal mass ejections). Other sources of ionizing radiation during air travel include radioactive cargo,radioactive substances released into the atmosphere as a result of a nuclear reactor accident or terrorist activity,lightning, and terrestrial gamma-ray flashes.A health effect following exposure to ionizing radiation for which the severity is radiation dose related is called adeterministic effect (non-stochastic effect, tissue reaction). Deterministic effects may occur soon after radiationexposure. For example, nausea and vomiting might be experienced by a space traveler a few hours after receivinga large dose of ionizing radiation while outside a space vehicle during a coronal mass ejection.If the probability (risk) of a health effect after exposure to ionizing radiation is dose related, it is called astochastic effect. Such effects seldom occur until years after the radiation exposure. Examples of stochastic effectsare cancer and genetic disorders. If one or both parents are irradiated prior to conceiving a child, there is a risk ofgenetic disorders in the child and in its progeny.The report can be used as a source book for instruction on ionizing radiation exposure of air and space travelers.119