Radon inside buildings in several regions of Portugal

Radon concentrations were measured continuously during large time intervals inside constructions in the North, Centre and South of Portugal covering several lithological regions with different uranium concentrations in rocks and soils. Average radon concentrations were high, above 5000 Bq/m(3) in some buildings at uranium regions, but very low as 10 Bq/m(3) inside buildings and workplaces in the Lisboa area, of sedimentary formation, and as low as 12 Bq/m(3) in the south of Portugal at sedimentary regions also. In view of the EU regulated radon concentration limit for indoor air, 300 Bq/m(3), the implications and way forward are discussed. Results strongly recommend a national radon plan aiming at identifying radon prone areas and reducing radon exposure to safe levels.