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.

中文翻译：

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测定切尔诺贝利污染的林木燃烧引起的大气中低137Cs浓度。

在净计数小于光谱背景的地方，使用γ光谱法测定空气中137Cs的低浓度至关重要。在切尔诺贝利山火期间，这些测量已于2020年4月进行。测得2020年4月12日在萨洛尼卡的大气中记录的一个重大事件，137Cs为25.7±0.7μBqm-3。此外，到2020年4月21日发生了137Cs浓度较低的轻微事件，浓度为9.6±0.8μBqm-3。以上结果类似于2013年冬季期间的先前结果，当时信号高达12.1±0.8μBqm-3。在大气中检测到的137Cs是由于广泛使用受污染的137Cs木材作为住宅供暖。所获得的结果表明，由于希腊塞萨洛尼基的空气中吸入了137Cs，对公众没有造成辐射危害。此外，已经估计了与气溶胶结合的137Cs的停留时间。所提供的数据对于基本的模拟输入以及与全球大气模型的比较非常有用，在与NOAA-HYSPLIT模型预测的反向轨迹进行比较之后，也进行了讨论。