Radon (Rn-222) is a naturally occurring radioactive gas belonging to the Uranium-238 (U-238) series. Due to the presence of Uranium-238 mainly in rocks and soils, radon forms mainly underground and tends to escape into the atmosphere. Radon concentrations in outdoor air (outdoor radon) are very low, of the order of a few Bq/m³, while inside buildings, especially in particular areas, it can reach even high concentrations in the air (indoor radon): for this reason, from a health point of view, radon is considered a typical risk factor in confined environments.
Indoor radon can be found in living and working environments, and in public buildings. The geological nature of the site, the type of construction of the building, the construction materials used, and the ventilation methods are among the parameters that most influence the concentration of indoor radon.
Radon risk assessment consists of measuring Radon concentrations in working environments over a period of one year. It is necessary when the work activity falls into one of the following categories with significant staff presence:
- Underground/sem basement workplaces
- Tunnels, subways, catacombs, caves
- Thermal establishments
- Workplaces located in specific areas considered at risk of exposure to Radon, regardless of the type of activity carried out
Given the high variability of the presence of radon in a room, a long-term measurement makes it possible to estimate the annual average concentration that takes into account temporal fluctuations, to be compared with the action values prescribed by the regulations. Generally, monitoring methods with passive dosimeters are used, which are placed in rooms for a certain period, after which readings are taken at the certified laboratory. The result gives the average concentration of radon present in the monitored room. In some cases, a short-term measurement may be useful for an initial check of the concentrations in the rooms of a building, and this can be carried out using portable active instrumentation.
The assessment of Radon risk in rooms is part of the risk assessment document. Therefore, as for any other risk, it should report the magnitude of the concentrations found, the comparison with legal limits and any actions to be taken to reduce the risk
