Caesium-137 alienation around the Chernobyl nuclear power plant. Together with caesium-134, iodine-131, and strontium-90, caesium-137 was among the isotopes distributed by the reactor explosion that constitute the greatest risk to health. The mean contamination of caesium-137 in Germany following the Chernobyl disaster was 2000 to 4000 Bq/m. This corresponds to a contamination of 1 mg/km of caesium-137, totaling about 500 grams deposited over all of Germany. In Scandinavia, some reindeer and sheep exceeded the Norwegian legal limit (3000 Bq/kg) 26 years after Chernobyl. As of 2016 the Chernobyl caesium-137 has decayed by half, but could have been locally concentrated by much
Radiation effects from the Fukushima Daiichi nuclear disaster caesium in most samples. From the 25 quarries in the evacuation zones, up to 122,400 becquerels of radioactive caesium was found at one that has been closed since the nuclear crisis broke out on 11 March 2011. In one quarry, that is still operational 5,170 becquerels per kilogram was found. Inspections were done at some 150 of the 1.100 construction sites, where the gravel form the Namie-quarry was suspected to be used. At 27 locations the radioactivity levels were higher than the surrounding area. On 6 May 2012 it became known that according to documents of the municipal education board