Radon Spatial Variations in University’s Buildings Located in an Italian Karst Region

Abstract

In the framework of a collaboration between INAIL and University of Salento, an indoor radon survey in 54 buildings belonging to the UniSalento University (Southeast Italy) was carried out. The monitored buildings differ by type, construction period, materials, etc., and are located in an area with a morphology characterized mainly by marls, calcareous marls, and calcarenites (karst area). The sample of the survey includes 963 rooms at different floors: it consists in rooms mainly located at ground floor (67%), first floor (12%), and below ground (12%). SSNTD passive dosimeters measured the average radon activity concentration for two consecutive semesters (spring/summer and autumn/winter) from which annual radon averages were estimated for each room. The spatial variability within buildings was investigated in terms of variation between floors and among rooms at the same floor. Data analysis provides evidence that the distributions (in terms of arithmetic mean, standard deviation, median, and geometric mean) of indoor radon annual averages at ground floor and at first floor within building are very similar. This highlights that the karstic characteristics of soil and building materials affect radon levels not only below ground and at ground floor, but also at first floor. Moreover, to evaluate the spatial variability of radon among buildings or floors, the analysis of the distribution of coefficient of variation (CV) was carried out: the results show a low spatial variability with median and average values of CVs ≤ 30% both for the whole building and at different floor levels.

Factors Affecting Indoor Radon Levels in Buildings Located in a Karst Area: A Statistical Analysis

“…This hypothesis seems to be supported by both the statistical evidences of the present analysis and the analysis carried out in Leonardi et al [16] on the same dataset. In that study, a very low spatial variability was found: homogenous radon levels were observed among rooms at all floors of 54 buildings, including 4 buildings far from Lecce and excluded in the present analysis.…”

“…A previous paper [16] reported the results of a radon survey carried out in a high number of buildings placed in a small part of an Italian karst area to evaluate the variations of indoor radon concentrations. These buildings present different characteristics in terms of year of construction, materials used, building size, and type of fixtures and heating system.…”

Temporal uncertainty versus coefficient of variation for rational regulation of indoor radon

“…In contrast with numerous studies of spatial variations in indoor radon, 22,27,34,[48][49][50][51][52][53][54][55][56] usually covering a large number of buildings, it would be much cheaper and less laborious to increase the frequency of data recording, that is, to carry out year-long monitoring by means of CRMs, albeit in a much smaller sample of buildings, given the subject of the study is temporal variations. For example, we assume that in Finland, it would be sufficient to conduct annual monitoring in 30-50 buildings, focusing on the data of Table 3 Table 4 shows how to rationally manage instrumental uncertainty U D using criterion (8).…”

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

“…Perhaps there are consistent patterns in the spatial behavior of radon across different rooms and/or floors in a building that could be statistically justified to enhance the applicability of criterion (1) for the entire building. However, all previously conducted [ 35 , 36 , 37 , 38 ] and planned studies (within the RadoNorm project) of spatial variations of radon within buildings still lack rigorous justification and clear outcomes from the perspective of the actual needs for indoor radon metrology and measurement standardization. Moreover, if the problem of conformity assessment of a room, as an elemental spatial and structural component of a building, remains not fully resolved, then the more comprehensive task of conformity assessment for an entire building solely based on patterns of spatial radon behavior evidently cannot have an effective solution.…”