Radon exhalation of untreated and aged Modica stone building material: a case study

In this paper, the assessment of the radon exhalation rate of the Modica stone building material, untreated and accelerated aged through salt crystallization test, is reported as a case study. Noteworthy, this construction material was largely employed for the construction of historical monuments of interest in the field of cultural heritage, especially in the historic city center of the Modica town, Sicily, Southern Italy, included in the UNESCO World Heritage list known as “Late Baroque Towns of the Val di Noto”. In detail, the Closed Chamber Method (CCM) with the Durridge Rad7 equipment for short-lived radon progeny alpha spectroscopy was employed to evaluate the radon exhalation rate of the investigated natural stone, and the Markkanen room model was used to calculate the potential indoor radon concentration based on the assessed rate value. Notably, the findings of this study can be employed to direct future research concerning the development of a systematic strategy for the radon content assessment in building materials, that turns out to be crucial for decision-makers, since it could be possible to identify vulnerable buildings requiring the use of well-defined protection measures.