explosion is when the nuclear fireball makes contact with the ground surface, with an explosion that does so, being aptly termed a surface burst. For example, in the Operation Crossroads tests of 1946 on Bikini Atoll, using two explosive devices of the same design and yield, the first, Test Able (an air burst) had little local fallout, but the infamous Test Baker (a near surface shallow underwater burst) left the local test targets badly contaminated with radioactive fallout. Widespread radioactive fallout itself was not recognized as a threat among the public at large before 1954, until the widely publicized story of the 15-megaton surface burst of the experimental test shot Castle Bravo on the Marshall Islands. The explosive yield of the Castle Bravo device the Shrimp was unexpectedly high and therefore correspondingly higher amounts of local fallout were produced. When this arrived at their location carried by the wind, this caused the 23 crew members on a Japanese fishing boat known as the Lucky Dragon to come down with acute radiation sickness with varying degrees of seriousness and due to complications in the treatment of the ship's radio operator months after the exposure, resulted in his death. It is, however, unlikely that a well-funded belligerent with nuclear weapons would waste their weapons with fuzing to explode below or on the surface, as both test shot Baker and Castle Bravo were respectively. Instead, to maximize the range of city blast destruction and immediate death, an air burst is preferred, as the ≈500 meter explosion heights of the only nuclear weapons used on cities, Little Boy and Fat Man also attest to. Moreover, with air bursts the total amount of radiation contained in the fallout, in units of activity/becquerel, is somewhat less than the total that would be released from a surface or subsurface burst, as in comparison, depending on the height of burst, little to no neutron activation or neutron induced gamma activity of soil occurs from air bursts. Therefore, the initial danger from concentrated local/'early' fallout (which takes on the color of the soil around the fireball, commonly with a dusty pumice or ash-like appearance, as experienced by the crew of the Lucky Dragon) remains low in a global nuclear war scenario. Instead the fallout most likely to be encountered by most survivors in this scenario is expected to be the less dangerous but widely spread global/'late' fallout. An air