Background radiation

Background radiation is a measure of the ionizing radiation present in the environment at an exact location which is not due to an intentional introduction of radiation sources.

All living things are exposed to natural ionising radiation from our surroundings. Normally we don't give this exposure much thought, because it comes from things in our everyday life we accept. There is a worldwide variation in the levels, but we will always be exposed to background radiation from natural sources in some scale. Globally this ranges from approximately 1 to 14 mSv per year. In addition to the natural background radiation, most humans are also exposed to artificial radiation as a consequence of industrial and medical activity; for example, x-ray.

Background radiation comes from a diverse number of sources, both natural and artificial. The sources include cosmic radiation and environmental radioactivity from such as naturally occurring radioactive materials, such as radon and radium, and man-made radioactive waste from nuclear weapons testing and nuclear accidents.

World average of natural background ionising radiation:
Sources: https://www.arpansa.gov.au/regulation-and-licensing/safety-security-and-transport/radioactive-waste-disposal-and-storage/what

https://en.wikipedia.org/wiki/Background_radiation