<P> The "duck and cover" countermeasure could save thousands . This is because people, being naturally inquisitive, would instead run to windows to try to locate the source of the immensely bright flash generated at the instant of the explosion . During this time, unbeknownst to them, the slower moving blast wave, would be rapidly advancing toward their position, only to arrive and cause the window glass to implode, shredding onlookers . In the testimony of Dr. Hiroshi Sawachika, although he was sufficiently far away from the Hiroshima bomb himself and was not behind a pane of window glass when the blast wave arrived, those in his company who were had serious blast injury wounds, with broken glass and pieces of wood stuck into them . </P> <P> Similar advice to "duck and cover" is given in many situations where structural destabilization or flying debris may be expected, such as during an earthquake or tornado . At a sufficient distance from a nuclear explosion, the blast wave produces similar results to these natural phenomena, so similar countermeasures are taken . In areas where earthquakes are common, a countermeasure known as "Drop, Cover, and Hold On!" is practiced . Likewise, in tornado - prone areas of the United States, especially those within Tornado Alley, tornado drills involve teaching children to move closer to the floor and to cover the backs of their heads to prevent injury from flying debris . Some US States also practice annual emergency tornado drills . </P> <P> The dangers of viewing explosions behind window glass were known of before the Atomic Age began, being a common source of injury and death from large chemical explosions . The Halifax Explosion of 1917, an ammunition ship exploding with the energy of roughly 2.9 kilotons of TNT, injured the eyes and faces of hundreds of people who stayed behind and looked out of their windows after seeing a bright flash, with 200 blinded by broken glass when the slower moving blast arrived . Every window in the city of Halifax, Nova Scotia, was shattered in this catastrophe of human error . </P> <P> In the Record of the "Nagasaki A-bomb War Disaster", those close to the hypocenter (Matsuyama township), were described as all having been killed, with the exception of "a child who was in an air - raid shelter ." A little further away, Professor Seiki of Nagasaki Medical School Hospital was building an air - raid dugout 400 m from the hypocenter of the detonation and survived . Chimoto - san, who was atop a distant hill that creates the valley in which Nagasaki is situated, performed the similar "hit the deck" maneuver upon seeing the bomb drop, which was notably prior to the detonation . However despite having these few seconds of relatively unique warning, he did not stay on the ground for long enough after the flash subsided, and received some translational injuries due to prematurely standing - up again, at which point the slower moving blast wave swept past him and carried him with it for a few meters . </P>

When did they stop duck and cover drills