RadonACCURACY · Accuracy assessment of the annual average indoor radon concentration based on measurements of different duration

Accuracy assessment of the annual average indoor radon concentration based on measurements of different duration

Radon is the most powerful source of natural radiation and dangerous carcinogen causing lung cancer. According to the recommendations of World Health Organization and EU Basic Safety Standards (EU BSS), the annual average indoor radon (AAIR) concentration should be limited to 300 Bq/m3. The national reference levels (RL) vary in different countries due to differences in regional levels of indoor radon and usually range from 100 to 300 Bq/m3. However, a reliable decision as to the compliance of estimated AAIR by test result with the RL remains an unsolved problem, since radon concentration in buildings has significant temporal variations (daily, weekly and seasonal) as seen in the Fig.1,2. This renders assessing the building compliance with radon safety criteria a serious challenge, and significantly complicates making an informed decision as to whether radon mitigation measures are needed. These unresolved issues greatly reduce the effectiveness of National Radon Action Plans established in Member States according to the requirements of the EU BSS. The most reliable assessment of a building’s compliance with radon safety requirements can be obtained with measurements taken continuously for a period of one year. However, in most buildings the radon level is only about 30 Bq/m3, i.e. significantly lower than the RL. Measuring low activity with high accuracy using the long-term tests is time-consuming and costly. It is true that the shorter the test, the higher the AAIR uncertainty. However, even a high uncertainty of up to 200% would be satisfactory in most cases due to the generally low level of radon in buildings (for example, 30 + 60 < RL). Only in relatively rare cases, where the high uncertainty of the short-term test does not allow for a reliable assessment of radiation safety, a decision must be taken based on more accurate long-term measurements. Obviously, such a decision should be supported by certain quantitative criteria based on the known values of AAIR uncertainty, depending on the test duration. Despite this important requirement, none of the national regulations (the measurement protocol in USA, Israel, ISO and IAEA recommendations) provide an assessment of the AAIR uncertainty depending on the test duration. Thus, the overall goal of the project is the assessment of the AAIR uncertainty based on the results of measurements with different duration and the development of rational (reliable) criteria for comparing the test result and RL. The overall goal of the project will be achieved as a result of implementing the following two research objectives: 1) definition of the values of the coefficient of temporal radon variation – K(t) 2) assessment of the influence of environmental factors on indoor radon behavior and determination the structure and values of the correction factor – k. Both parameters are used in our first proposed radon control principle shown in Fig.3.

Data: CORDIS, © European Union