Fukushima Daiichi nuclear disaster casualties of radioactivity released into the atmosphere was approximately one-tenth as much as was released during the Chernobyl disaster. Significant amounts of radioactive material have also been released into ground and ocean waters. Measurements taken by the Japanese government 30–50 km from the plant showed caesium-137 levels high enough to cause concern, leading the government to ban the sale of food grown in the area. Tokyo officials temporarily recommended that tap water should not be used to prepare food for infants. In May 2012, TEPCO reported that at least 900 PBq had been released "into the atmosphere in March, 2011 alone."
Fukushima Daiichi nuclear disaster On 13 February 2014, TEPCO reported 37 kBq (1.0 microcurie) of caesium-134 and 93 kBq (2.5 microcuries) of caesium-137 were detected per liter of groundwater sampled from a monitoring well. Dust particles gathered 4 km from the reactors in 2017 included microscopic nodules of melted core samples encased in caesium. After decades of exponential decline in ocean caesium from weapons testing fallout, radioactive isotopes of caesium in the Sea of Japan increased after Fukushima from 1.5 mBq/L to about 2.5 mBq/L and are still rising as of 2018, while those just off the western coast of Japan have declined. According