Radon

Radon is a naturally occurring radioactive gas that seeps from the soil into buildings through cracks, joints, and penetrations in the foundation. Radon is colorless, odorless, and tasteless, making it impossible to detect without specialized measurement equipment. It is produced by the radioactive decay of uranium, which is present in all soils and rocks but in varying concentrations depending on the local geology.

Long-term exposure to elevated radon concentrations is the second leading cause of lung cancer after smoking, according to the World Health Organization. In Finland, radon levels are among the highest in Europe due to the prevalence of uranium-bearing granite bedrock and glacial till soils. The Finnish Radiation and Nuclear Safety Authority (STUK) recommends that indoor radon concentration should not exceed 200 becquerels per cubic meter (Bq/m3) in existing buildings and 100 Bq/m3 in new construction.

Radon measurement is simple and inexpensive. Alpha-track detectors are placed in the lowest occupied level of the building for a two-month measurement period during the heating season (October to April), when radon levels are highest. Continuous electronic monitors provide real-time readings. Every homeowner should measure radon at least once, and remeasure after any major renovation that affects the foundation or ventilation system.

If elevated radon levels are found, mitigation methods include sub-slab depressurization (installing a fan to extract radon-laden air from beneath the foundation slab and vent it outdoors), sealing foundation cracks and penetrations, and improving ventilation. Sub-slab depressurization is the most effective method, typically reducing radon levels by 70 to 90 percent. A radon mitigation specialist can design the most appropriate solution for your building.