The document states that ionizing radiation from natural sources, such as radon, thorons, cosmic rays, and natural radionuclides in soil and food, constitutes the main part of the radiation burden on humans. While anthropogenic sources generally contribute less, they can be significant during major nuclear incidents.
Extensive Study
The findings are reflected in a new scientific annex from UNSCEAR titled "Assessment of Exposure of the Population to Ionizing Radiation." This is currently the most comprehensive global analysis of exposure from both natural and anthropogenic sources, based on data from studies conducted between 2007 and 2022.According to estimates, the average global annual dose of radiation from natural sources is approximately 3.0 millisieverts (mSv). The main contribution to this figure comes from inhalation of radon, thoron, and their radioactive products—about 1.8 mSv per year. Other sources include natural radionuclides from food and water (0.5 mSv), external exposure from radionuclides in the Earth's crust (0.4 mSv), and cosmic radiation (0.3 mSv).
The new estimate exceeds the previous global average estimate published in 2008, which was 2.4 mSv. However, UNSCEAR points out that the increase is related to improved data quality and methodology, rather than an increase in the environmental radiation background.
According to UNSCEAR Chair Dr. Sara Baatout, "the new assessment provides a clearer and more representative picture of the radiation doses that people receive in their daily lives. With better quality data and scientific advancements, we can more accurately assess exposure levels and contribute to public health protection."
Impact of Anthropogenic Sources
The report also notes that the impact of anthropogenic sources, including medical, scientific, and industrial applications of radiation technologies, under normal operating conditions amounts to only a few microsieverts per year.Exposure for people living near nuclear power plants remains low and generally does not exceed tens of microsieverts per year. The effective dose per unit of electricity generated is 0.4 person-sieverts per gigawatt-year.
Nuclear Testing
The radiation levels in areas where nuclear tests were conducted have significantly decreased. While exposure was high immediately after the tests, annual doses at sites in New Mexico, the Marshall Islands, Mururoa, Fangataufa, and Semipalatinsk are now generally below natural background levels.Chernobyl and Fukushima Accidents
Exposure related to the Chernobyl and Fukushima nuclear accidents continues to decrease due to natural decay processes and decontamination measures. Currently, annual doses in areas around Chernobyl range from tens of microsieverts to several millisieverts, while in non-evacuated municipalities near Fukushima, they range from a few microsieverts to approximately 0.3 mSv.This UNSCEAR report aims to provide governments and international organizations with relevant scientific data to develop effective policies in radiation protection and public health.
Illustration on the main page: Unsplash / N. Hurst.
