ABSTRACT
On the exterior, radon tends to scatter, exhibiting lower concentrations, usually below 10 Bq/m3, whereas inside the dwellings, radon’s concentration may reach levels well above 400 Bq/m3 or even 1000 Bq/m3, for this gas has the ability to infiltrate through the soil to the inside of dwellings through cracks, poorly sealed joints and drainage infrastructures. Recent constructions are also better sealed to assure better thermal stability and energetic savings, resulting in a higher exposure. Since radon is denser than air, it has the ability to build up on the lower floors of the dwellings (Dias et al. 2009, Ferreira et al. 2006). Changes on radon’s concentration levels along the year also occur. On the winter, concentration levels are frequently higher due to less airing on the dwellings. The opposite situation is evidenced outside the dwellings, that is, on the summer concentrations on the exterior are higher than on the winter due to the rise of temperature and fall of humidity (Rêgo, 2004).
