At FMPI CU, health is protected by measuring radon
When indoor air quality is discussed, attention usually focuses on dust or CO₂. In Slovakia, however, the radioactive gas radon also represents a significant risk. We spoke with Associate Professor Monika Müllerová from the Department of Nuclear Physics and Biophysics at the Faculty of Mathematics, Physics and Informatics of Comenius University Bratislava (FMPI CU) about why measuring radon concentrations in kindergartens and homes matters, how field research is carried out, and why renovations of older buildings should not be underestimated.
Radon in indoor environments has recently been discussed more intensively in Slovakia. Is this a new threat, or have we simply overlooked the issue for a long time?
Radon has been present since the earliest stages of the Earth. It is a naturally occurring radioactive gas produced by the decay of uranium in the soil. In Slovakia, the first large-scale measurements were carried out in the early 1990s. At that time, Dr M. Vičanová conducted extensive radon research as part of her doctoral thesis under the supervision of Associate Professor K. Holý from our department, measuring radon levels in kindergartens, schools, caves, spas and thousands of homes.
These measurements resulted in useful maps of high-risk areas, but today they are no longer sufficient. Since then there has been no systematic nationwide effort - only smaller projects carried out at the department - so the maps need updating and, above all, measurements must increasingly be carried out individually. The problem is not the presence of radon itself but its accumulation in enclosed spaces. We are returning to the topic today because the situation has changed significantly: buildings are being insulated and windows replaced, which can have a major impact on radon concentrations indoors.
You are currently carrying out measurements in kindergartens in regions such as Orava, Prievidza and Partizánske. Why focus specifically on pre-school facilities?
At present we are measuring radon levels in 29 kindergartens. Children are far more sensitive to ionising radiation than adults. Their lungs have a different capacity and their tissues are still developing. Exposure to high doses during childhood increases the statistical risk of lung cancer later in life. Kindergartens also operate under specific conditions. They are closed at weekends and not ventilated, which allows radon to accumulate to high levels. Our aim is to establish the real situation and help the authorities responsible for these facilities ensure a safe environment for children. In this work we cooperate with the Association of Towns and Municipalities of Slovakia and the League Against Cancer.
How do such measurements work in practice? Do schools need to worry about complicated technology?
Not at all. We use so-called track detectors. These are small, unobtrusive boxes placed in rooms for several months, ideally for the entire school year. The detectors passively record the presence of radon and require neither electricity nor operation. Once the detectors are collected, they are analysed in the laboratory, which allows us to determine the average radon activity over the monitored period. If borderline values are detected, we also install continuous detectors that monitor radon concentrations every hour and help identify when and from where the gas enters the building.
What are the most common sources of radon? Is it always just the ground beneath the building?
Soil gas is the main source. Radon is a gas and can pass through even the smallest cracks in foundation slabs, around service risers or along water pipes. A second possible source is the building materials themselves, for example certain older types of concrete blocks. Modern renovations can also create a paradoxical situation. When an older, naturally ventilated house is insulated and fitted with plastic windows, radon that previously escaped freely may remain trapped inside.
Is there a safe threshold? What happens if high levels are detected in a kindergarten or a home?
Slovak legislation sets a reference level of 300 becquerels per cubic metre per year. If this level is exceeded, corrective measures must be taken. In many cases, adjusting the ventilation regime is sufficient. Several solutions are possible, but the first step is always to identify the source of the radon. This is done through supplementary measurements with a continuous detector that records hourly changes in concentration. Our researchers do this quite simply: they attach a hose to a pump that draws air into the detector and move through the rooms to locate cracks through which the gas enters. The Czech Republic is somewhat ahead in this field. Since the 1990s it has adopted more advanced methods, which are often presented at professional conferences. Today, basic radon monitoring devices for households are also available to the public, which is an excellent first step. Where extremely high levels are detected, technical solutions follow, such as radon insulation layers, special membranes or ventilation systems with heat recovery.
You mentioned that some people are hesitant about measurements or afraid of the results. What would you say to them?
We sometimes encounter the attitude: “I’d rather not know.” That is unfortunate, because radon cannot be seen or smelled, yet its effects on health are well documented. Encouragingly, the situation is changing. Requests for measurements are now coming from the authorities responsible for kindergartens, which shows that awareness campaigns are increasing public understanding. The measurements we offer as part of our scientific projects are free of charge and serve primarily preventive purposes. Our aim is not to frighten people but to inform them. Once we know the enemy, we can defend ourselves against it effectively.
What are your department’s next plans in this area?
We plan to continue the measurements and further refine the map of radon risk in Slovakia. The existing maps are often inaccurate, and radon is highly localised—levels can change even within a few metres of soil, meaning that neighbouring houses may have completely different readings.
We are therefore looking for ways to involve additional municipalities and towns in these projects. It is a long-term effort, but we believe that systematic work by the university can contribute to healthier living conditions in Slovakia. The research is conducted in cooperation with expert partners, and all measurements follow the National Radon Action Plan. Anyone interested in having measurements carried out in their facility or home can contact the Department of Nuclear Physics and Biophysics at FMPI CU directly.