Validation of aerosol low-level activities by comparison with a deep underground laboratory.

Abstract The activities on air filters of the radionuclides 40 K and 137 Cs were measured in an above ground laboratory and compared with the activities measured in an underground laboratory. The average relative differences were lower than 20% for 137 Cs and 40 K. The temporal series of these radionuclides in the period 2006–2010 are also presented. These results form the baseline of these radionuclides in the studied period, and are particularly interesting because they correspond to the radioactive background in Barcelona before the Fukushima accident.