To determine the radon levels in a school or kindergarten, the person responsible for the building or its day-to-day operations must ensure that a radon measurement is carried out.
Frequently occupied rooms have to be measured. Examples are classrooms, playrooms, offices, dining rooms/canteens and teaching rooms such as music rooms, woodwork rooms and gymnasiums.
Measurement protocol for radon in schools and kindergartens
Measurements taken according to DSA’s protocol for radon measurements in schools and kindergartens document the radon levels.
Radon must be measured regularly. When new measurements are taken, the applicable measurement protocol must be followed.
Limit value and action level for radon
The Radiation Protection Regulations lay down requirements for radon levels in primary and secondary schools and kindergartens, both public and private.
All schools and kindergartens should keep their radon levels as low as reasonably achievable, and the annual average radon level should be below 200 Bq/m³ (becquerels per cubic metre) 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 the measurements show radon levels higher than 100 Bq/m³, whether they are 150, 400 or 2000 Bq/m³, you must ensure that measures are taken to keep the levels as low as reasonably achievably. In any event, the levels should not exceed the limit value of 200 Bq/m³.
Provided that documentable radon measures have been implemented, the radon level can be between 100 and 200 Bq/m³.
After measures have been taken to reduce the radon level, it must be re-measured to check that the measures have had sufficient effect.
The radon requirements in the Radiation Protection Regulations are a strengthening of the regulations on environmental health protection in schools and kindergartens. The municipalities constitute the primary supervisory authority. DSA can also exercise supervision.
Long-term measurement is important
An investigative radon measurement must always be carried out as a long-term measurement in the winter months between mid-October and mid-April. By long-term measurement, we mean that the measurement period must last for at least two months or longer.
Radon concentrations in indoor air vary from day to day and from week to week. A long measurement period like this is needed to capture this natural variation. This is the case whether the measurement is carried out with etched track detectors or electronic measuring instruments.
If an electronic device is used, it should be treated in the same way as an etched track detector. There must be one device per measurement point and the device should be in the same place for the whole measurement period.
Short-term measurements over just a few days or weeks risk not capturing periods with high radon concentrations. Short-term measurements are therefore unsuitable for assessing which rooms need to be prioritised for long-term measurement. Measurements taken over less than two months will also not provide a basis for calculating the annual mean value and so cannot be used as documentation of measurement activity.
However, short-term measurements over just a few days can be used to assess the effect of measures or study variations during the day and the radon-reducing effect of the ventilation system.
The limits apply to frequently occupied rooms
The limit value and the action level in the Radiation Protection Regulations apply to frequently occupied rooms. Frequently occupied rooms are rooms that are used more than occasionally. Obvious examples are classrooms, playrooms, offices, dining rooms/canteens and teaching rooms such as music rooms, woodwork rooms and gymnasiums.
Hallways and corridors may also be defined as frequently occupied rooms if they are widely used, such as a corridor outside classrooms or in a kindergarten where children play. Sometimes you have to use your discretion to judge whether or not a room is frequently occupied.
Examples of rooms which are not frequently occupied are technical rooms, toilets and store rooms.