Castle Bravo
The decision to carry out the Bravo test under the prevailing winds was made by Dr. Alvin C. Graves, the Scientific Director of Operation Castle. Graves had total authority over detonating the weapon, above that of the military commander of Operation Castle. Graves appears in the widely available film of the earlier 1952 test "Ivy Mike", which examines the last-minute fallout decisions. The narrator, the western actor Reed Hadley, is filmed aboard the control ship in that film, showing the final conference. Hadley points out that 20,000 people live in the potential area of the fallout. He asks the control panel scientist if the test can be aborted and is told "yes", but it would ruin all their preparations in setting up timed measuring instruments. In Mike, the fallout correctly landed north of the inhabited area but, in the 1954 Bravo test, there was a large amount of wind shear, and the wind that was blowing north the day before the test steadily veered towards the east.
Project GABRIEL
During the Cold War era, there was an escalation of the atmosphere testing of nuclear weapons. After the atomic bomb in 1945, testing continued and the scale increased with the first hydrogen bomb in 1952. Soon after the United States tested the hydrogen bomb, the USSR followed, in 1953. The mushroom clouds that occurred from the explosions released radioactive isotopes in mass quantities.
The first comprehensive study of this problem began in spring 1949 with a one-man project called GABRIEL, conducted by Nicholas M. Smith Jr. at Oak Ridge National Laboratory. Smith produced his first report in 1949. Project GABRIEL was revived in mid-1951 because bombs that were dropped had brought up concerns people had about the dangers of strontium-90. United States Atomic Energy Commission (AEC) was interested by GABRIEL's report though they said it was lacking in hard data and needed independent confirmation of the tests.
After reviewing Project GABRIEL in 1953, it was given first priority status. The secret project would define "practical limits" for using atomic weapons. A task team was assembled and the codename used was "Project HORN." In 1954, AEC argued that fallout was harmless because there wasn't enough evidence to prove that fallout would harm humans, animals, or crops. The AEC campaign persuaded the public that the worldwide fallout was harmless. This claim was later disputed when scientists announced publicly that there was no safe level of radiation. This was confirmed in a confidential report by a geneticist for the AEC. By 1954 and the Castle Bravo incident, it was obvious that radioactive fallout was dangerous to humans. United States Atomic Energy Commission Division of Biology and Medicine dealt with efforts directed towards experimental and field studies and the correlation of data dealing with Project GABRIEL.
The RAND Corporation, Laboratories at Columbia University, AEC's New York office, the University of Chicago, an exclusive group of scientists, UCLA, and the United States Air Force were all involved in collection and testing of samples from around the world for radioactive fallout.