Radon is causing natural radioactivity
Natural radioactive substances are everywhere. One of these is uranium found in the bedrock and soil. When uranium gets degraded several new radioactive materials are forming (uranium chain). The final product is stable lead. We find radon in this chain.
Radon is radioactive noble gas
Radon is a gas that has little ability to bind to solids. Radon atoms can therefore easily escape and get into the air we breathe.
Why is radon a problem?
Radon can be problem in kindergartens, schools, homes and workplaces.
The reason lies in soil conditions with alum shales and uranium containing granite. Combined with sand and soils, in Norwegian building customs, this has brought us to the top of the world in radon problems.
Norwegian plan and building regulations
PBL §8 - 33, section 1 general requirements:
Ground building structures shall be performed in the way that contaminations from the ground can not penetrate into the construction works and health.
PBL §8 - 33, section 4 radon:
Building design should ensure that people who are living in a building can not be exposed to radon concentration indoors because it may increase the risk to human health.
Guideline to technical regulations of plan and building as specified in §8 - 33:
Contaminants supplied from indoor air in the building ground are preliminary humidity and radon.
Structures that are in contact with the ground must be performed very tight so that contamination from the ground can not penetrate into the construction works and cause health risks.