What is radon and what risks does it pose?
\n
\nIt is a colorless, radioactive gas that is produced by the natural decay of uranium and thorium – radioactive elements commonly found in rocks and soils. Uranium is widely used, for example, as fuel for nuclear reactors.
\n
\nThis gas is completely tasteless and odorless and is released from the earth’s crust. Due to its higher density than air, it tends to accumulate near the ground and easily penetrates the interiors of buildings through leaks in their construction.
\n
\n
\n
\n
\n
\n
Czech Republic: A country with one of the highest occurrences of radon in the world
\nThe Czech Republic is among the areas with the highest concentration of radon in the world. This is due to the geological composition of the substrate, particularly the presence of uranium ores, granites, and other rocks rich in radioactive elements.
\n
\nFor this reason, strict standards and regular inspections of indoor spaces in buildings are in place to minimize the risks associated with exposure to this dangerous gas. The highest concentrations of radon can be found in areas such as the Bohemian-Moravian Highlands, the Ore Mountains, or the Jizera Mountains.
\n
\n
\n
\n
\n
\n
\n
\n
\n
Why is radon dangerous?
\nRadon is considered a very serious carcinogen, and long-term exposure to environments with elevated concentrations can have serious impacts on human health. However, radon itself is not the main danger – the problem lies with its decay products, known as radon daughters. These radioactive particles can attach to dust and be inhaled into the lungs, where they subsequently irradiate lung tissue. Short-term exposure, however, poses only a negligible risk.
\n
How does radon enter buildings?
\nRadon naturally occurs in the substrate and groundwater. It can enter indoor spaces through:
\n
\n- cracks in foundations and floors,
\n
\n- through basements,
\n
\n- pipes and waste systems,
\n
\n- water taps and showers (especially if using well water),
\n
\n- other leaks in the building’s construction.
\n
\n
\n
How is radon measured and in what units?
\nRadon is measured in Becquerel (Bq), named after the French physicist Henri Becquerel, who discovered natural radioactivity. The Bq unit expresses one radioactive decay per second.
\n
\nFor measuring radon exposure in indoor environments, the unit Bq/m³ (Becquerel per cubic meter) is used. For example, 1 Bq/m³ means that in a volume of one cubic meter, one radioactive decay occurs every second.
\n
Radon measurement can be conducted in two ways:
\n
\n \t
Short-term measurement: Immediate-read detectors are used, providing quick results.
\n
\n2. Long-term measurement: Passive detectors that record the average concentration of radon over a longer period (usually 1–12 months).
\n
Radon limits in indoor environments in the Czech Republic
\nAccording to the decree of the State Office for Nuclear Safety No. 184/1997 Coll., the following limits apply:
\n
\n \t
Existing buildings: The average value of radon volume activity should not exceed 400 Bq/m³. If this limit is exceeded, measures to reduce the concentration are recommended.
\n
\n2. New buildings: For new constructions, a stricter limit of 200 Bq/m³ is set. Therefore, preventive measures against radon infiltration must be implemented during construction.
\n
\nThese limits are in accordance with the recommendations of the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO).
\n
\n*Interesting fact: The average radon level in apartments in the Czech Republic is approximately 120 Bq/m³.
\n
Radon risk map
\nAreas with high radon occurrence are now well mapped. On the radon risk maps of the Czech Republic, which are available on the websites of the State Office for Nuclear Safety (SÚJB) or the Czech Geological Survey, you can easily find out whether your home is located in a zone with low, medium, or high risk.
\n
\nYou can find one such map here: http://www.geologicke-mapy.cz/radon/
\n
How to reduce radon concentration indoors?
\nThe key to a safe environment is adequate ventilation. The ideal solution is controlled ventilation based on current values measured by a radon sensor, such as the ADS-RN3. This device allows for effective ventilation without unnecessary energy loss.
\n
\nOther measures include:
\n
\n- sealing cracks in floors and walls,
\n
\n- installing radon barriers during the construction of new buildings,
\n
\n- using sub-slab depressurization, which effectively removes radon from the building.
\n
\nPractical example: Passive house in a risk area
\n
\nMeasurements in a passive house showed that the radon concentration was highest on the ground floor, reaching nearly 1,000 Bq/m³, while in the attic it remained around the limit of 200 Bq/m³. The highest values were measured in the basement – up to 4,000 Bq/m³, which was the main source of radon in the living areas. Due to natural air flow, radon concentrations in the attic are usually lower. After implementing ventilation, the values throughout the house were reduced to a safe level.
\n
\nConclusion
\n
\nRadon is an invisible enemy that can have serious health impacts. However, with modern technologies such as radon sensors and controlled ventilation, its concentration can be effectively monitored and risks to residents minimized. It is also important to conduct regular measurements, especially in areas with high radon risk, and to take appropriate measures to reduce exposure.
