The document indicates that ionizing radiation from natural sources, such as radon, thorons, as well as cosmic rays and naturally occurring radioactive materials in soil and food, account for the majority of radiation doses received by the population. In contrast, exposure levels from anthropogenic sources are generally much lower unless major nuclear or radiological incidents occur.
Global Radiation Analysis
The findings are presented in a new scientific annex of UNSCEAR titled "Assessment of Population Exposure to Ionizing Radiation." This study is the most comprehensive global analysis of radiation doses from both natural and man-made sources and is based on data from the Global Survey of Population Exposure and an analysis of scientific publications from 2007 to 2022.The committee estimates the average global annual effective dose of exposure from natural sources to be approximately 3.0 millisieverts (mSv). The main contributors are radon, thoron, and their decay products, which account for about 1.8 mSv per year. The next most significant contributions come from radionuclides in food and water (0.5 mSv), external exposure from radionuclides in the Earth's crust (0.4 mSv), and cosmic radiation (0.3 mSv).
This figure exceeds the previous global average estimate of 2.4 mSv published in 2008. UNSCEAR notes that the increase is related to improved data quality and methodology, rather than an increase in natural background radiation.
“The new assessment provides a more accurate and representative picture of the exposure that people face in their daily lives,” says Dr. Sarah Baas, chair of UNSCEAR. “With better quality data and scientific advancements, we can better assess exposure levels and support efforts to protect public health at national and international levels.”
The Role of Man-Made Sources
The report also emphasizes that the contribution of man-made sources, such as medical, scientific, and household use of radiation technologies, under normal operating conditions amounts to only a few microsieverts per year.Exposure doses for residents near nuclear power plants remain extremely low and typically do not exceed tens of microsieverts per year. The collective effective dose per unit of electricity generated is estimated at 0.4 person-sieverts per gigawatt-year.
Nuclear Testing
Radiation levels in areas where nuclear tests were conducted have significantly decreased. While exposure was high at the beginning of the tests, current annual doses at test sites in New Mexico, the Marshall Islands, Mururoa, and Fangataufa, as well as in Semipalatinsk, are usually much lower than the natural radiation background.Chernobyl and Fukushima Accidents
The situation with exposure levels related to the Chernobyl and Fukushima disasters is also improving due to radioactive decay and decontamination. Currently, annual doses in areas around Chernobyl range from tens of microsieverts to several millisieverts, while in municipalities near Fukushima, they range from a few microsieverts to approximately 0.3 mSv.The UNSCEAR report serves as a source of up-to-date scientific information for governments and international organizations, aiding in the development of policies on radiation protection and public health.
Illustrative photo on the main page: Unsplash / N. Hurst.
