Radon in workplaces in Extremadura (Spain)

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Abstract

Indoor radon measurements are usually associated with housing. However, a typical person spends about one-third of the day at their workplace. A survey was made of radon levels in workplaces in Extremadura (Spain). More than 200 measurements were performed in some 130 firms and organizations of different sectors (urban wellness centres, spas, caves, mines, water management facilities, underground carparks, wine cellars, museums, etc.). Activated charcoal canisters and track detectors were used for sampling. The results indicated the importance of performing this type of measurement because the exposure of workers can reach high values in some cases.

Highlights

More than 200 measurements were performed in about 130 working places. ► Activated charcoal canisters and track detectors were used for sampling. ► The exposure of workers can reach high values in some cases. ► Geological characteristics of the soil influence the indoor radon levels.

Introduction

Human beings are constantly exposed to natural radiation sources. Radon (we shall use “radon” to mean 222Rn for the sake of simplicity) is the main source of natural radiation, and the second leading cause of lung cancer after smoking (Zeeb and Shannoun, 2009). Indoor radon measurements are generally associated with dwellings. However, a typical person spends more than eight hours a day in their workplace, so that it is recognized as essential to monitor workers' exposure to radon to control their health risks (ICRP, 1993). There have been some surveys measuring indoor radon in dwellings and public buildings such as schools and offices (Llerena et al., 2010; Rafique et al., 2010), in workplaces (Clouvas et al., 2007; Papachristodoulou et al., 2010; Thinova and Rovenska, 2011; Vaupotič, 2008), and, for our region of Extremadura in particular, some studies of radon concentrations in buildings carried out by other researchers (Baeza et al., 2003).

In Spain, radon concentration measurements are compulsory in workplaces according to the provisions of a recently issued regulation establishing recommendations and limits related to natural sources of radiation. This regulation requires the managers of professional activities involving such sources to carry out studies to determine whether there is any significant increase in the exposure of workers or of members of the public, and which may be considered as non-negligible from the point of view of radiological protection. The Spanish Nuclear Security Council (CSN) has defined which places may be at especial risk of exposure to radiation and to radon levels above the limits considered as safe (Sanz Alduán and Ramos Salvador, 2008). In particular, remedial action must be taken in places where the 222Rn annual average activity concentration is above 400 Bq/m3. In the case of workplaces frequented by the public, the limit level is 200 Bq/m3 for recently constructed buildings, and 400 Bq/m3 for previously existing buildings.

We have carried out a survey measuring radon in workplaces in the region of Extremadura (Spain) as part of an R&D project in nuclear safety and radiation protection. This paper presents the characteristics of the monitoring procedure and the results, showing the importance of the need to measure radon concentrations in workplaces.

Section snippets

Detectors

Measurements were carried out using two types of probes: activated charcoal canisters (short-term exposure) and CR-39 nuclear track detectors (long-term exposure). The activated charcoal canisters allowed fast measurement (two-days exposure), which is used to quickly identify places with a significant concentration of radon, while the nuclear track detectors (three-months exposure) provided estimates for the annual average concentrations which are the values considered by the legislation.

The

Results and discussion

More than 200 determinations were performed (in some companies several rooms were analysed). Only one canister was lost. However, only 67% of the track detectors were collected in good condition. The problem appeared to be the long time that this type of detector had to be left at the measuring site. An added difficulty is that the company cannot detain its normal activities during the measurement period. In particular, cleaning, painting, improvement works, and other similar actions were

Summary and conclusions

A survey was carried out to determine indoor radon concentrations in workplaces, with more than 200 measurements corresponding to about 130 companies in Extremadura (Spain). Two types of detector were used: canisters and track detectors. The canisters were used for the fast identification of “hot points”, because the exposure time needed was only two days. The track detectors allowed us to determine the average annual concentration for each site, because the exposure time was three months. This

Acknowledgements

Thanks are due to the Spanish Consejo de Seguridad Nuclear (CSN) for financial support, and to the members of the University of Cantabria for collaborating with their readings of the track detectors. Special acknowledgement is due to the managers of the companies who collaborated in the study, for facilitating the conditions for the measurements.

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