  After the earthquake and the tsunami occurred in Japan on 11th March 2011,
four of the Fukushima reactors had released in air a large amount of
radioactive isotopes that had been diffused all over the world. The presence of
airborne 131I, 134Cs, and 137Cs in air particulate due to this accident has
been detected and measured in the Low Radioactivity Laboratory operating in the
Department of Environmental Sciences of the University of Milano-Bicocca. The
sensitivity of the detecting apparatus is of 0.2 \mu Bq/m3 of air.
Concentration and time distribution of these radionuclides were determined and
some correlations with the original reactor releases were found. Radioactive
contaminations ranging from a few to 400 \mu Bq/m3 for the 131I and of a few
tens of \mu Bq/m3 for the 137Cs and 134Cs have been detected

Medical Physics