Short‐ versus long‐term tests of indoor radon for risk assessment by Monte‐Carlo method towards effective measurement strategy

Abstract

There now exists a broad consensus among the European radon community members that long-term measurements are the best practice in managing the risk of indoor radon exposure. This, not with standing the fact that <1% of buildings have been tested in Europe so far. At the same time, US' experience over the years shows more effective regulation has been accomplished through tests that are short-term. This study quantifies the uncertainty of collective risks obtained independently through short-and long-term measurements under the same conditions using the Monte Carlo method that takes into account the number of measurements, as well as the diversity of the spatial distribution of radon concentrations in representative samples of buildings. Simulation results have shown that contrary to the erroneous practice of the European radon community, the accuracy of the assessment of the collective risk due to radon exposure does not in fact depend on the duration of the indoor test at all. The main problem remains ensuring the existance of a representative sample of buildings, especially given limited number of tests. In this regard, recommended is a revision of the regulatory documents of IAEA, ICRP, WHO, and ISO focusing on (i) the principle of the effective measurement strategy based on rational ISO/IEC concepts, (ii) the mass measurements via short-term tests, and (iii) the societal engagement in measurements.

Metrology for Indoor Radon Measurements and Requirements for Different Types of Devices

“…For the first time, the rational criterion for conformity assessment was introduced at Final Symposium COST NETWORK “NORM4Building” in Rome (6–8 June 2017) over 6 years ago. The authors have been consistently refining, and striving to promote, the rational criterion through publishing the results of their studies in journals [ 10 , 16 , 17 , 27 , 32 ] and presentations at conferences, for example, (i) the 29th Conference of the Nuclear Societies in Israel (6–8 May 2018), (ii) the Ninth International Symposium on Naturally Occurring Radioactive Material (NORM IX, 23–27 September 2019, Denver, CO, USA), (iii) a EURAMET EMPIR meeting (PRT MetroRadon II, 22–23 January 2020, BEV, Vienna, Austria), (iv) European Radon Week 2020 (24–28 February 2020, BEV, Vienna, Austria), (v) the 2020 VIRTUAL International Radon Symposium, Plug in to Recharge (9–13 November 2020, AARST, US), (vi) the 6th European Congress on Radiation Protection (30 May–3 June 2022, Budapest, Hungary), (vii) AARST Symposium (24–26 October 2022, Bellevue, WA, USA), and (viii) RAD 11 (19–23 June 2023, Herceg Novi, Montenegro). In addition, the authors actively participate in the ISO working group [ 16 ].…”

“…Moreover, the extensive results from short-term indoor radon tests in each US state allow for high-resolution detailing of RPAs [ 19 ] and assessing collective risks without the need for long-term measurements. This approach is not only theoretically justified [ 17 ] but practically confirmed by the fact that there are only minor differences between the indoor radon map based on short-term tests and the map refined based on a complete set of geological data [ 20 ]. Thus, the detailing of RPAs is quite achieved through a large number of indoor radon measurements, regardless of the duration of the tests [ 17 ].…”

“…This approach is not only theoretically justified [ 17 ] but practically confirmed by the fact that there are only minor differences between the indoor radon map based on short-term tests and the map refined based on a complete set of geological data [ 20 ]. Thus, the detailing of RPAs is quite achieved through a large number of indoor radon measurements, regardless of the duration of the tests [ 17 ].…”

“…Indeed, an analysis of the literature published over the past decades indicates that in Europe [ 17 ], the priority of surveys is detailing the location of Radon Priority Areas (RPAs), as well as assessing and refining collective risks, rather than identifying hazardous buildings and implementing indoor radon mitigation, in contrast to the US, where mitigation has been carried out in several million buildings [ 18 ]. Moreover, the extensive results from short-term indoor radon tests in each US state allow for high-resolution detailing of RPAs [ 19 ] and assessing collective risks without the need for long-term measurements.…”

“…In contrast to the evident advantages of the US regulation compared to the European one, there persists a lingering skepticism among many specialists (regulators) in using the short-term measurements [ 17 ]. A significant drawback shared by both US and European measurement protocols, including ISO 11665-8, is the failure to account for a temporal uncertainty of indoor radon.…”