Determination of low 137Cs concentration in the atmosphere due to Chernobyl contaminated forest-wood burning

The determination procedure of low 137Cs concentrations in air using γ-spectrometry is essential wherever the net counts are smaller than the background of the spectrum. Such measurements have performed in April 2020 during the Chernobyl wildfires period. A significant event recorded in Thessaloniki's atmosphere during April 12, 2020, with 25.7 ± 0.7 μBq m−3 of 137Cs, was measured. Besides, a minor incident with a lower 137Cs concentration of 9.6 ± 0.8 μBq m−3 has occurred on April 21, 2020. The above results resemble to a previous one noticed during winter 2013, when signals up to 12.1 ± 0.8 μBq m−3 of 137Cs detected in the atmosphere, due to extensive use of 137Cs contaminated wood for residential heating. The results obtained demonstrate that no radiation hazard rose for the general public due to inhalation of the 137Cs in the air of Thessaloniki, Greece. Moreover, the residence time of the aerosol-bound 137Cs has estimated. The data presented are useful for basic simulation-inputs and comparison with global atmospheric models, which also discussed after comparison with the back trajectories predicted by the NOAA-HYSPLIT model. •Low 137Cs determination in air.•Chernobyl forest fires.•137Cs contaminated biomass.•Residence time of 137Cs.•Back-trajectories.