Line 2 aims to continue to improve knowledge. The publication in 2018 of a new map on the municipal scale, based on three radon-potential zones, enabled a graded approach to radon risk management to be implemented. This map must nevertheless be improved so as to better integrate certain geological factors that could facilitate radon transfer to buildings (karst zones in particular). Furthermore, the 4th Radon Plan provides for the updating of knowledge of exposure of the French population by organising the collection of measurement data obtained in particular during the local awareness-raising operations organised by the ARS and the regional authorities to cover the areas for which insufficient data are available. These operations consist in proposing screening kits to the inhabitants of a given region to raise their awareness of the radon risk. Lastly, line 3 aims to take better account of the management of the radon risk in buildings. In order to help members of building trade organisations improve their skills, these organisations have recently developed training courses dealing with methods to prevent and reduce concentration levels and various media to address the needs. The various French-language aids have been listed. To supplement the offering, a guide intended for professionals and private individuals alike was published in 2023. It provides recommendations concerning prevention in new constructions and remediation in existing buildings. The progress made in understanding the effectiveness of construction standards in reducing radon concentrations in indoor air shall be consolidated. A system of specific indicators, chosen according to their relevance and the data available for monitoring them, has been put in place. Monitoring how these indicators evolve over several years will enable the effectiveness of the national strategy deployed under the national action to be determined. The first assessment of the indicators was published in September 2024 (see box previous page). 3.3 Doses received by patients In France, exposure for medical purposes represents the greatest part of the artificial exposures of the public to ionising radiation. It has been regularly reviewed by IRSN since 2002. Although exposure has been increasing for the last 30 years, it has tended to stabilise since 2012, whereas at the same time the number of medical procedures has greatly increased. Nuclear medicine, the third-biggest contributor to the collective effective dose, is the discipline that saw the greatest increase between 2012 and 2017, in terms of both frequency and contribution to the collective effective dose. The average effective dose per inhabitant resulting from diagnostic radiological examinations was evaluated at 1.53 mSv for the year 2017 (IRSN ExPRI study 2020) for some 85 million diagnostic procedures performed in 2017 (81.6 million in 2012), i.e. 1,187 procedures for 1,000 inhabitants per year. It is to be noted that as before, the individual exposure in 2017 is very varied. Consequently, although about 32.7% of the French population underwent at least one procedure (dental procedures excluded), half the patients received a dose of 0.1 mSv or less, 75% received 1.5 mSv or less, while the most exposed 5% of patients received a dose exceeding 18.1 mSv. Conventional radiology (55.1%), computed tomography (12.8%) and dental radiology (29.6%) account for the largest number of procedures. It is the contribution of computed tomography to the effective collective dose that remains preponderant and more significant in 2017 (75%) than in 2012 (71%), whereas that of dental radiology remains very low (0.3%). In adolescents, conventional radiology and dental procedures are the most numerous (about 1,000 procedures for 1,000 individuals in 2017). Despite their frequency, these procedures in this population represent only 0.5% of the collective dose. Lastly, it will be noted that: ∙A national headcount estimated at more than 30,000 patients was exposed to a cumulative effective dose of more than 100 mSv in 2017 due to multiple computed tomography examinations. This figure reaches 500,000 if a cumulative period of six years is considered. This highly exposed population seems to be increasing in size regularly and relatively rapidly since 2012. Although most people in this population are old, a quarter of them are aged under 55 years. The question of possible radiation- induced effects in the long term is therefore raised for this specific population. It is worth pointing out that these patients are often suffering from serious pathologies and that the computed tomography examinations are important for their care. ∙Based on a sample of 120,000 children born between 2000 and 2015, IRSN reports that in 2015, 31.3% of the children in the sample were exposed to ionising radiation for diagnostic purposes (up by 2% compared with 2010). The average effective dose is estimated at 0.43 mSv and the median at 0.02 mSv (down for the average but equivalent for the median value). TABLE 5 Number of procedures and associated collective effective dose for each imaging method (rounded values) in France in 2017 Imaging method Procedures Total collective effective dose: 102,198 Sv Number % % Conventional radiology (dentistry excluded) 46,681,000 55.1 11.8 Dental radiology 25,023,000 29.6 0.3 Computed tomography 10,866,000 12.8 74.2 Diagnostic interventional radiology 435,000 0.5 2.4 Nuclear medicine 1,662,000 2.0 11.3 Total 84,667,000 100.0 100.0 Source: IRSN, 2020. DIAGRAM 5 Distribution of the initial and ten-yearly measurement by PAB category from 2016-2017 to 2023-2024 0.3% Spas 11.9% Day-care facilities for children under 6 years of age 0.5% Prisons 59.8% Schools 27.5% Certain health care, social and medico-social facilities 114 ASN Report on the state of nuclear safety and radiation protection in France in 2024 Nuclear activities: ionising radiation and health and environmental risks
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