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Radon in other living areas

Radon in other living areas

The aim of radon monitoring in other indoor areas is to ensure that no Finn is overly exposed to radioactive radon gas, which can cause lung cancer. The municipality's health authorities supervise compliance with the reference values for radon levels in dwellings and other living areas (Radiation Act 859/2018, § 15).

Other living area

Other living area means a space that is a public assembly room or other space intended for long-term residence (Health Protection Act, Section 13). Typical other public places are schools, churches, libraries, swimming pools and, for example, gyms.

Other living areas where the radon concentration must be determined (Radiation Act 859/2018 156§)

The indoor radon concentration must be determined at least in the following other living areas:

  1. All other living spaces that are partly or completely underground.
  2. In areas where at least 10 % of the annual average radon concentrations measured are greater than the reference value of 300 Bq/m³. The Radiation and Nuclear Safety Authority (STUK) maintains a list of these areas.
  3. In other living areas located on ridges or other highly permeable gravel or sand formations throughout the country.

The responsibility concerning the obligation to investigate is in accordance with the provisions of Section 27(2) of the Health Protection Act concerning the investigation, elimination and limitation of health hazards.

Radon measurement is not normally necessary in other living areas on the second or upper floors of a building. If the floor and walls of the building are not in contact with the ground and good ventilation of the intervening space is evident, radon measurements are not required.

Measuring radon concentration

Indoor radon concentration is primarily determined using an alpha track detector, i.e., a radon measuring box (integrating measurement), kept in the other living space for at least two months between the beginning of September and the end of May. The radon measurement detector gives an average of the long-term concentration.  If necessary, the temporal variation of radon concentrations can then be determined by so-called continuous radon measurement.

The key is to use a reliable measurement method to determine radon concentration. Radon measurement can be ordered from an operator using a measurement method approved by STUK.

How often should radon be measured?

The average radon concentration in a property can therefore change for many reasons. STUK therefore recommends that indoor radon measurements be repeated in other living areas, workplaces, and dwellings

  • every ten years if the previous radon concentration was higher than 100 Bq/m³;
  • every 10 years if the reduction of the radon concentration below the reference value has been achieved by radon mitigation;
  • every five years if the radon concentration below the reference value has been achieved by radon mitigation and the radon concentration before mitigation was greater than 1000 Bq/m³;
  • as soon as possible after any substantial structural or ventilation work (e.g., replacement of concrete slab, drainage or ventilation).
  • Pressure conditions in the building may also change, for example after window replacement: if there was significant leakage of replacement air through the old window openings, the new, tight windows may increase the negative pressure in the room, reduce ventilation and significantly increase radon levels.

STUK is aware of cases where a radon detector has failed without anyone noticing. As a result, human exposure to radon has remained at the same high level as before the radon mitigation.

Radon reference value and limitation of radon concentrations

The reference value for indoor radon concentration in dwellings and other indoor living areas is 300 becquerels per cubic meter (Bq/m3). The radon concentration in the other living areas is calculated as the annual average radon concentration during the period of use.

The owner and occupier of the building must ensure that the radon concentration in the indoor air of the other living areas is as low as possible, taking into account the circumstances.

Measures to be taken after radon measurement

The results of radon measurements in the other living areas must be submitted to the municipal health protection authority. If the other living space is also someone's work space, and if the radon measurement has been ordered from a private radon measurement company, the results of the radon measurements must be reported to STUK without delay, via STUK's e-service (https://stukasiointi.stuk.fi/asiointi/en/). If the radon measurement in other living areas has been carried out by STUK's radon measurement service, the radon measurement service sends a test report to the subscriber and submits the measurement results to STUK's radon monitoring of workplaces. Radon measurements ordered from STUK do not have to be reported separately to STUK.

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