Prevention of major risks and natural hazards - Radon risk

Radon was discovered in 1900 by physicist Friedriech Ernst Dorn.

It is a naturally occurring, odorless and colorless radioactive gas with atomic number 86 (chemical symbol Rn), produced by the decay of radioactive metals (uranium and radium) present in the rocks that make up the earth's crust.

It reaches the soil surface through cracks in rocks and through the porous layers of the ground through which it passes. It can also be dissolved in water.

The atoms of this gas disintegrate, emitting particles and generating solid radioactive particles. It comes mainly from granitic and volcanic subsoils, but can also be found in certain building materials. It accounts for only a third of public exposure to ionizing radiation. It can accumulate in confined, poorly ventilated spaces (mines, underground galleries) and also in certain parts of buildings: under a slab on grade, in a crawl space, a basement, a room on the first floor, etc.

The radon risk was long ignored because the effect of underground radioactive ores was not suspected.

Inhalation of radon and its solid progeny accounts for a third of the population's average exposure to ionizing radiation. It is the leading cause of irradiation among natural sources of radiation.

It's a natural source of irradiation on which man can technically act.

Radon can also be found in water, but when it comes into contact with air, it degasses. Radon thus enters the body, mainly through inhaled air, and more rarely through drinking water. However, epidemiological studies have so far failed to establish a link between radon in drinking water and the risk of cancer.