Radon is an inert gas that is a natural decay product of uranium, and it can build up in enclosed spaces such as workplaces and homes. For most people, radon is the largest source of radiation exposure throughout their lifetime. Radon is the also the second biggest cause of lung cancer, after smoking, and the leading cause of lung cancer among non-smokers. Level of exposure to radon depends on the geology of an area and the materials used in the construction of buildings.
But just how much does radon affect health? To answer this question, information about radiation dose to lungs is crucial. To calculate this dose, national regulatory authorities normally use dose conversion factors, which convert measured activity concentration into radiation dose, and this information helps them to decide what radiation protection measures, if any, are necessary for a given location.
Dose conversion factors are also used in the IAEA’s General Safety Requirements on Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (GSR Part 3 or BSS) for the control of radon exposure. The BSS aims to serve as reference for Member States developing relevant national regulations on radiation protection, and are based on the scientific information published by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and recommendations issued by the International Commission on Radiological Protection (ICRP).
Last year ICRP, an independent, international, non-governmental organization with the mission to provide recommendations and guidance on radiological protection concerning ionising radiation, published new, higher dose conversion factors for radon, which therefore increase the calculated radiation dose associated with exposure to radon in workplaces. Its recommendations on exposure in homes are under preparation.
UNSCEAR, however, has confirmed in a report on lung cancer from exposure to radon earlier this year that the evidence reviewed by its experts is compatible with the available data in the Committee’s previous assessment of lung cancer risk due to radon. Therefore, UNSCEAR concluded that there is no reason to change its established dose conversion factor. This new report was approved by the Fourth Committee of the United Nations General Assembly in October 2019.
Based on this new development, the IAEA held an expert meeting last month to seek the advice of experts on the potential implication of the ICRP recommendations on BSS requirements.
“There is a real appetite for clarity among Member States around this particular issue,” said David Fenton, senior scientist with the Irish Environmental Protection Agency’s Office of Radiation Protection and Environmental Monitoring, who attended the meeting. “In Ireland, we regard it important to ensure policies that implement the Basic Safety Standards (GSR Part 3) are in line with best international practices.”
The experts concluded that there is no immediate need to change the relevant radiation protection requirements in the BSS. They also recommended that the IAEA and the organizations that co-sponsor the BSS develop a position paper on the use of dose conversion factors for radiation protection.
Subsequently, the IAEA Radiation Safety Standards Committee (RASSC), which advises on and reviews IAEA safety standards in the field of radiation safety, agreed with this recommendation at its 20 to 22 November meeting.
RASSC also echoed the call for a position paper on the subject to assist Member States in this area. The IAEA and the co-sponsors of the BSS are now considering this request.
