Logistic of surveys of retrospective radon concentrations by home-stored CDs/DVDs

Evaluation of citizen science contributions to radon research

In order to reduce lung cancer due to radon exposure situations, not only authorities and organisations but also citizens may meaningfully contribute to radon mitigation actions. Citizen science (CS) initiatives are recognised for their scientific, societal and policy value related to environmental issues. The purpose of this paper is to identify which CS initiatives in the field of radon exist and evaluate to what extent these CS initiatives contribute to radon research and/or radiation protection from radon. We conducted a systematic review of internet pages and scientific literature (September-December 2020) as well as expert consultation to help us identify and assess CS initiatives on radon (September 2020-February 2021). The ten principles of the European Citizen Science Association have been used as a starting point to develop indicators for the analysis of CS contributions to radon research. The results show that there are at least eight CS initiatives in the world contributing to radon related research which comply, to some degree, with each of the ten principles. In all these initiatives citizens contributed or are contributing meaningfully to radon testing and measurements. However, most of them apply the simplest form of participation (crowdsourcing) and only one focuses on radon mitigation. Moreover, unlike CS initiatives in other environmental areas, those focusing on radon are always led by the authorities and/or universities, in a top-down manner. Yet, results confirm that both the experts in radon-related fields and the citizen scientists from radon prone areas benefit from taking part in radon CS initiatives. Experiences and lessons learned in radon related to CS initiatives are identified and discussed in order to inspire future CS initiatives potentially contributing to reducing exposure to radon as well as to the implementation of national radon action plans.

Identifying radon priority areas and dwellings with radon exceedances in Bulgaria using stored CD/DVDs

The implementation of the 2013/59/EURATOM directive in the part related to radon exposure imposes challenges for radon measurement methodology and radon survey design. Among them is the need to have estimates (preferably direct) of the annual average radon concentrations, which can be directly compared to the recommended reference levels. On this basis, the surveys should make possible the identification of dwellings with indoor radon above the reference levels and "radon priority areas" where significant proportion of the dwellings falls in this category. The performance of the CD/DVD method for radon measurements as a tool to address these issues is presented. A recent large scale field study based on the CD/DVD method that was carried out in the suburb area of Sofia, Bulgaria is described. Part of the studied area was affected in the past by the uranium mining and milling industry. In total 462 disks (CDs and DVDs) taken from 335 private dwellings from 10 districts in the region were analyzed. The results revealed the large heterogeneity in radon distribution in the area, with the percentage of dwellings with a ²²²Rn level above 300 Bq m^-3 ranking from about 7% to 74%. The district of Yana, for which this percent was 74, was identified as the area of highest radon priority in the region. The paper also discusses how prompt identification of dwellings with radon above the reference level by CD/DVDs can be incorporated within an integrated approach to the radon problem. Within this approach the radon hazard is identified shortly after the stakeholder's decision to test, which allows fast solution of the problem without waiting the long (and usually demotivating) one-year period needed for direct results by the commonly used prospective methods.

Energy-efficient reconstructions and indoor radon: the impact assessed by CDs/DVDs

Recent modelling suggests that the expense of energy-efficient building reconstructions can be the enhanced indoor radon levels and the related adverse health impact. Here we show that a couple of home-stored CDs/DVDs can be used to check by direct measurements whether a significant change in radon level occurred in the past after building reconstruction. Radon is continuously absorbed in the polycarbonate material of CDs/DVDs and its average concentration can be determined by etching alpha tracks at a certain depth in the disk. With two disks, one bought before and one after the reconstruction, a change in radon concentration can be detected retrospectively. Within a pilot study of 20 rooms in 16 buildings that underwent energy-efficient interventions years in the past, we observed significant increase in radon concentration (at 95% confidence level) in 35% of the cases, and no case with significant decrease. Direct indication of a radon problem emerged after some of the energy-efficient building interventions was observed. The CD/DVD based approach provides a tool for assessment of the effect of different energy-efficient reconstruction approaches on indoor radon in very short terms and could be useful for finding radon-safe energy-efficient options.