IN SHORT
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A radon measurement is the only way to determine whether a home has a radon problem.
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All landlords are responsible for ensuring that the radon level in the rental accommodation is as low as reasonably achievable.
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Flats on and above the second floor above ground level do not usually need to be measured.
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The radon requirements apply to all types of rental accommodation: public, commercial and private sectors, including flats and bedsits adjacent to private homes.
Limit value and action level for radon
The radon level in rental accommodation should be as low as reasonably achievable. The annual average radon level should be below 200 Bq/m³ (becquerel per cubic meter) in frequently occupied rooms. This is the statutory limit value set by the Radiation Protection Regulations.
Moreover, measures to reduce the radon level must always be taken if it exceeds 100 Bq/m³. This is the statutory action level set by the Radiation Protection Regulations. This means that if you measure radon levels higher than 100 Bq/m³, whether they are 150, 400 or 2000 Bq/m³, you need to take steps to keep the levels as low as reasonably achievable. In any event, the levels should not exceed the limit value of 200 Bq/m³.
Provided that documentable radon measures are implemented in the home, the radon level can be between 100 and 200 Bq/m³. If you have taken measures to reduce radon in the home, you must take fresh measurements to check that the measures have had sufficient effect.
Applicable to all types of rental accommodation
The requirements for radon apply to all types of rental accommodation: public, commercial and private sectors, including flats and bedsits adjacent to private homes.
Cottages and holiday homes
Rented cottages and other holiday homes are not covered by the requirements for radon. However, this assumes that they are only used for leisure purposes over a short period. If the cottages/holiday homes are used as dwellings, they will be covered by the requirements.
Measuring radon in rental accommodation
To determine the radon level in rental accommodation, the landlord must ensure that a radon measurement is carried out. This is done in the same way as a private home.
Flats on and above the second floor above ground level do not usually need to be measured.
Radon should be measured during the winter months, between mid-October and mid-April. The measurements should take place over a period of at least two months. If it turns out after measurements are taken that the levels are above the action level, documentation must be provided to show that radon mitigation measures have been implemented or that action is under way.
- Radon measurements in residential dwellings
Here you can also download DSA’s measurement protocol for dwellings (in Norwegian only). Measurements carried out according to this protocol document radon levels.
Documentation of radon levels
Landlords should be able to provide proof that radon levels are reasonable. The documentation shall not be registered with the authorities, but it should be kept and be available to the tenant and for supervisory purposes.
Supervision
The municipality has the authority to inspect for radon in rental accommodation and will normally be regarded as a local supervisory authority. DSA can also exercise supervision.
Housing cooperatives and condominiums
If an owner or co-owner rents out a condominium or cooperative apartment, they are covered by the radon requirements in the Radiation Protection Regulations. However, if they live in the apartment and do not rent out any part of it, they are not covered by the requirements. DSA advises everyone to measure radon at home in any case, and to take the necessary measures.