Radon in a flat: measurement, limits and risk areas
Von Lumi · Aktualisiert: 16. Juni 2026, 00:00 UTC
Radon is an odourless indoor-air risk, highest on the lowest floors. How to spot the risk, measure it, and read STUK's limits.
Dieser Ratgeber beschreibt Regeln und Praxis in Finnland.
This guide is only available in English.
Wichtig: On the lowest and ground-contact floors radon can exceed the limit without symptoms — measure before buying.
Radon is a radioactive gas that rises from the ground into indoor air. It's odourless and invisible, but long exposure is a health risk. In Finland levels vary by area.
Where radon comes from
Radon travels from the soil into a building's lowest spaces. The risk is highest in ground-contact and lowest floors; upper apartments typically have low levels.
Limits (STUK)
STUK reference values: in an existing home the action level is 300 Bq/m³, and a new building is designed so radon stays under 200 Bq/m³. The WHO recommends below 100 Bq/m³.
The median varies by municipality — around 100 Bq/m³ in the capital region, clearly higher in some areas.
How to measure and act
Radon is measured with a detector over at least two months (three recommended) between September and May. If the value exceeds the limit, mitigation (sealing or a radon sump) is usually effective. Lumi shows the municipal median by address.
Häufig gestellte Fragen
- Is radon dangerous in an apartment building?
- Upper floors usually have low levels; the risk mainly concerns the lowest and ground-contact spaces.
- What is the radon action level?
- 300 Bq/m³ in an existing home (STUK); a new one is designed below 200 Bq/m³, and the WHO recommends below 100.
- How is radon measured?
- With a radon detector over at least two months (three recommended), September–May.
Quellen
Siehe auch
Dieser Ratgeber bietet allgemeine Informationen, keine individuelle Beratung. Zahlen und Regeln bei offiziellen Quellen prüfen.