Radon is a radioactive, colourless, odourless, tasteless noble gas, and it can’t be perceived by our senses. It occurs naturally from the decay of Uranus-238, that is present in variable quantity on Earth’s crust. Its more stable isotope is Radon-222 which decays in few days, emitting ionizing radiations, specifically alpha
particles. It forms its “progeny” or decay products, among which Polonium-218 and Polonium-214, which also emit alpha particles. Radon’s radioactivity is measured in Becquerel (Bq): 1 Bq corresponds to the transformation of an atomic nucleus per second. Concentration in the air is expressed in Bq/m 3 that indicates the number of transformations that occur in am 3 of air. OMS, together with the International Agency for Research on Cancer (Iarc) classified radon in the first group of cancerogenic substances for humans.

Health effect

The main damage on human’s health linked with radon exposition is lung cancer. Worldwide radon is considered the most dangerous radioactive contaminant indoor and it has been estimated that averagely 50% of the human exposition to ionizing radiations is caused by radon.

Radon diffusion

Radon emitted from the sole outdoor is dispersed in the atmosphere. Radon levels indoor are always higher than radon levels outdoor. This is because radon is almost eight times heavier than air, so it cumulates indoor, driven by the difference between pressure and temperature that is created in the sole outside the structure and inside. There are other factor linked to radon presence in an environment among which geological characteristic of the sole, construction characteristic (e.g. walls permeability), inhabitants, life style and behaviours.

Importance of measuring

The more the radon indoor, the more the time we spend in a place, the higher the risk. In order to obtain a
significant evaluation of the average radon level in a house or a building it is necessary to take into account
that the concentration varies during the day (generally it is higher during night time) or seasonally
(generally higher in winter time). Therefore it is fundamental to prolong measurement at least for one year.