Background radiation
![The weather station outside of the Atomic Testing Museum on a hot summer day. Displayed background gamma radiation level is 9.8 μR/h (0.82 mSv/a) This is very close to the world average background radiation of 0.87 mSv/a from cosmic and terrestrial sources.](/Images/godic/202501/11/Atomic_Testing_Museum_weather_display_cropped2843.jpg")
![Estimate of the maximum dose of radiation received at an altitude of 12 km January 20, 2005, following a violent solar flare. The doses are expressed in microsieverts per hour.](/Images/godic/202501/11/Sievert-sigle2843.png")
![Displays showing ambient radiation fields of 0.120-0.130 μSv/h (1.05-1.14 mSv/a) in a nuclear power plant. This reading includes natural background from cosmic and terrestrial sources.](/Images/godic/202501/11/Kozloduy_Nuclear_Power_Plant_-_Background_radiation_displays2843.jpg")
![Per capita thyroid doses in the continental United States resulting from all exposure routes from all atmospheric nuclear tests conducted at the Nevada Test Site from 1951-1962.](/Images/godic/202501/11/US_fallout_exposure2843.png")
Background radiation is the ubiquitous ionizing radiation present in the environment. Background radiation originates from a variety of sources, both natural and artificial. Sources include cosmic radiation, naturally occurring radioactive materials such as radon, and fallout from nuclear weapons testing and nuclear accidents.