Within a 3-day period in August 1945, atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki, killing a total of 64 000 people within 1 km of the explosions as a result of blast, thermal effects, and instantaneous γ and neutron irradiation.
Scott, in Encyclopedia of Toxicology (Third Edition), 2014 Atomic Bomb Survivors For this reason, plutonium nuclides were considered initially to be only a minor hazard thus far, fewer detailed measurements of 239,240Pu in air or on the earth's surface have been made compared to other fallout radionuclides, especially 90Sr.ī.R. The data in Table 2 indicate that the release of a total of ∼11.5 PBq (1.1×10 16 Bq) of 238,239,240Pu represented only a tiny fraction of the total of ∼250 EBq of radioactivity released by nuclear weapons testing. The amounts of these nuclides dispersed in the atmosphere as a result of nuclear weapons testing are shown in Table 2. In the next half-century, most of the shorter-lived radionuclides decayed, leaving only 90Sr and 137Cs, and the plutonium isotopes, as the major fallout nuclides. The fallout from such weapons amounted to a total of ∼250 EBq (2.5×10 +20 Bq) and contained a broad spectrum of radionuclides with half-lives ranging from a few days, 131I, to many years, including 90Sr, 137Cs and 238Pu, 239Pu, 240Pu and 241Pu.
The explosion of the second atomic bomb, Fat Boy, above Nagasaki on 9th August 1945 began the widespread release of plutonium into the atmosphere, but by far the largest contribution came from the atmospheric testing of more than 500 atomic and thermonuclear weapons between then and the end of the 1970s.
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