Radon emits ionizing radiation as a result of the natural decay of uranium-238 that is part of the rocks in the Earth’s crust. From the subsoil it rises and can leak into homes and workplaces through cracks, fissures and poorly sealed joints. Sometimes it reaches concentrations that are dangerous to health, so it is worth wondering how much radon is in our homes and workplaces.
Radon is a type I human carcinogen (demonstrated association) causally linked to lung cancer. The relationship between exposure to radon and The risk of this type of cancer is dose-response.: the more exposure, the greater the risk. The first studies were carried out in miners during the last century and were subsequently carried out in the general population until confirming that people exposed to high concentrations of radon in their homes had a higher risk of lung cancer.
There are multiple factors that influence the concentration of radon in indoor spaces, but the most important is the uranium content in the rocks of the Earth’s crust on which buildings sit and the degree of insulation of the building with the ground.
Spain is slow to apply European directives
In 2013 the European Union published the Directive for Protection against Ionizing Radiationswhich established an application period of until February 2018. In addition, it established a maximum reference level of 300 becquerels per cubic meter (Bq/m³) for homes and workplaces, among other aspects.
Spain has implemented this directive very late, in December 2022, with a Royal Decree that obliges employers to protect workers against exposure to radon. Specifically, it requires that it be measured in all underground workplaces, through laboratories accredited by the National Accreditation Entity (ENAC).
Furthermore, in municipalities in priority areas it is necessary to carry out measurements on ground floors. The priority areas must be indicated by the Nuclear Safety Council. We are currently awaiting the designation of these locations. Everything seems to indicate that they will be those indicated as type II by the Technical Building Code, located mainly in Galicia, Madrid, Extremadura, Castilla y León and Catalonia.
In the event that radon levels exceed 300 Bq/m³, the Royal Decree requires that mitigation actions be implemented to protect and reduce the exposure of workers.
Is radon exposure high at work?
The largest study carried out in Spain on this topic was published in 2023. Includes data on 3,140 jobs in 14 Spanish provincesalthough the majority located in Galicia.
In our work, one in five jobs exceeded 300 Bq/m3. Differences were observed between sectors: the most exposed to radon were the cultural and educational sectors; the least, the financial and textile. As expected, the concentration of the gas decreased as the position moved away from the underground: 30% of underground workers would have exposures above 300 Bq/m³, compared to 17% on the first floors.
The geographical location of the work space according to the classification of the municipality is also essential. While 21% of the positions in municipalities with high radon potential exceeded 300 Bq/m³, this percentage was only 1% when they were located in other areas.
It should be noted that extreme radon concentrations, above 1000 Bq/m³, were found in 4% of all workplaces included in this study.
To what extent does it pose a health risk?
The available evidence indicates that the relationship between radon and lung cancer is linear. The latency period between exposure to the gas and the appearance of symptoms can extend decades (at least 20 years of high exposure) so that the risk of lung cancer can increase significantly.
We also know that there is an important interaction between radon exposure and tobacco use. In fact, most lung cancer cases attributed to radon occur in smokers and former smokers. Therefore, if the exposed person has never smoked, their risk, although it exists, is lower than that of a smoker.
Finally, the fact that the person exposed at work may have a high radon concentration in their home must also be considered. Especially if you live in an area with high radon potential and on a ground floor.
This does not eliminate the obligation that the employer currently has to evaluate and reduce the concentration of that gas as efficiently and quickly as possible. This can be achieved, in the vast majority of situations, in a simple way.
In short, the measurement of radon gas and its mitigation (when applicable) is an obligation on the part of employers as part of protecting the health of workers. Fortunately we know how it is measured, how it is reduced and how it affects health. There is no longer an excuse to apply regulations and achieve a healthier work environment in the face of a carcinogen that has always been there, but to which not enough attention has been paid.
This article was originally published in The Conversation. You can read it here.
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