Radiological data on building stones from a Spanish region: Castilla y León

Abstract

Abstract. As construction and building material, natural stone has a great potential to promote the commercial activities of certain European regions. Such is the case of Castilla y León in Spain, where many different rocks, ranging from sedimentary to metamorphic and igneous, are commercialized for building purposes. However, to be able to compete in a market subject to an economic crisis, highly exacerbated in the construction sector, and to compete with the lower prices offered by emerging countries, the issue would be to make the Spanish offer more attractive. Here we propose a complete characterization of rocks regarding their radiological properties, which are related to their mineralogy and geochemistry. Rocks emit natural radioactivity, and the presence of Rn and its decay products in dwellings has become an important issue in North America and Europe owing to its relationship with the carcinogenic effects of this gas. Although most of the studied rocks comply with the I parameter proposed in the European Norm 112 for Radiological Protection (accepted value I ≤ 1; average for sedimentary rock: I = 0.22, SD 0.14; average for metamorphic rocks: I = 0.70, SD 0.48; average for igneous rock: I = 0.86, SD 0.22), the inclusion of a proper radiological characterization in the list of characteristics would guarantee quality and safety in their use in comparison with products lacking this information. Some natural stones have been demonized for the potential exhalation of natural radioactivity, and the different parameters used should be addressed in a more systematic way.

Natural radioactivity and radon exhalation rate of Sardinian dimension stones

“…The sample with the highest Ra activity concentration was Giallo San Giacomo (Leucogranite), even though the radon exhalation rate was not the highest compared to other samples. This can be explained by taking into account the textural features, fractures and weathering state of the rock [6,32,34], which determine the possibility for radon atoms to escape from the surface of the Ra-bearing minerals or remain trapped within the rock. In fact, when a 226 Ra atom decays a Rn atom is formed together with an alpha particle [3].…”

“…Therefore, real-time measurements of 222 Rn exhalation rates need to be performed in order to estimate the actual risk associated to a given natural stone [5]. Those measurements must be performed on samples in the form of blocks or slabs, as grounding the rock increases the specific surface and decreases the grain size, thus producing an overestimation of the radon exhalation rate and consequently a false alarm about the actual risk associated to the material under investigation [6].…”

Is there any health danger by radioactivity on the use of dimensional stones?

“…The median value of the SF samples is given in in bold. The literature data refer to: Bundesamt für Strahlenschutz (2020), Marocchi et al (2011), Madruga et al (2019), Weng (1996), Rafique et al (2014), Pereira et al (2013) A( 226 Ra) A( 232 Th)…”

“…The radioactivity of the samples is related with mineralogical composition. Therefore, large variations can be expected considering the rock types and the content of radiogenic accessory minerals (Marocchi et al 2011;Pereira et al 2013;Sanjurjo-Sánchez and Alves 2017;Maden et al 2019). Several compilations of concentration values can be found in literature, which emphasizes the natural variations among the rocks (Pereira et al 2012;Turhan 2012;Trevisi et al 2012;Sayın 2013;Qureshi et al 2014;Puccini et al 2014;Todorovic et al 2015;Sanjurjo-Sánchez and Alves 2017;Al-Hamarneh 2017;Moghazy et al 2021).…”

Geological Materials as Sources of Rn Emissions

“…The consulted publications presented results of mass exhalation rates or surface exhalation rates or both (few publications) from diverse types of rocks. Granites are the rock type most frequently considered (Allen et al [3]; Chauhan [4]; Marocchi et al [5]; Moura et al [6]; Pereira et al [7,8]; Bavarnegin et al [9]; Pereira et al [10]; Rafique & Rathore [11]; Guillén et al [12]; Marques et al [13]; Andrade et al [14]), but there are also studies that include other igneous rocks (Chauhan [4]; Marocchi et al [5]; Moura et al [6]; Pereira Gómez et al [7]; Rafique & Rathore [11]; Guillén et al [12]), with a predominance of pyroclastic rocks (studied in Marocchi et al [5] ]; Andrade et al [14]; Turhan et al [15]; Kayakökü et al [16]. There are some studies with results on metamorphic rocks such as marbles (Bavarnegin et al [9]; Rafique & Rathore [11]; Andrade et al [14]) and silicate metamorphic rocks (Chauhan [4]; Marocchi et al [5]; Pereira et al [10]; Andrade et al [14]), and also some studies that include information in sedimentary rocks being (Bavarnegin et al [9]; Pereira et al [10]; Andrade et al [14]).…”