Duck and cover

[1] In the classroom scene of the film, the rapid employment of school desks, as an improvised shelter following the awareness of the initial light flash, is a countermeasure primarily to offer protection from potential ballistic window glass lacerations when the slower moving blast wave arrived.

The Halifax Explosion of 1917, an ammunition ship exploding with the energy of roughly 2.9 kilotons of TNT,[22] 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.

[26] Chimoto-san, who was atop a distant hill that creates the valley in which Nagasaki is located, 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.

Thus, although the advice to duck and cover is over half a century old, ballistic glass lacerations caused the majority of the 1000 human injuries following the Chelyabinsk meteor air burst of 15 February 2013.

"Duck and cover" exercises quickly became a part of Civil Defense drills that every US citizen, from children to the elderly,[dubious – discuss] was encouraged to practice[citation needed] so that they could be ready in the event of nuclear war.

Therefore, they are thus considered to present an overestimate of the lethal ranges that would be encountered in an urban setting in the real world,[46] with this being most evident following a ground burst with explosive yield similar to first generation nuclear weapons.

Upon observing the nuclear weapons silent flash she quickly lay flat on the ground, while those who were standing directly next to her, and her other fellow students, had simply disappeared from her sight when the blast wave arrived and blew them away.

[39][60] For example, Sumiteru Taniguchi recounts that, while clinging to the tremoring road surface after the Fat Man detonation, he witnessed another child being blown away, the destruction of buildings around him and stones flying through the air.

Ms. Karbysheva, who herself did not duck and cover but remained standing, was seriously lacerated when the explosion's blast wave arrived, and window glass blew in, severing a tendon in one of her arms; however, not one of her students, who she ordered to hide under their desks, suffered a cut.

[64] A follow-up study of the effects of the meteor airburst determined that the windows most prone to breaking when exposed to a blast overpressure are those of school buildings, which tend to be large in area.

However, even the thinnest of barriers such as cloth[75][76][77] or plant leaves would reduce the severity of burns on the skin from the thermal radiation with the flash light, similar in average emission spectrum/color to sunlight.

[88][89][90] While the propagating fires in both Japanese cities were almost exclusively ignited by the blast wave overturning charcoal cooking-braziers and similar secondary events, thermal flash-fires from untreated fabric and timber in the urban environment is considered potentially the widest destructive effect of the higher yield explosive devices.

[75] In the only human accounts at these high luminous intensities that are not of the more common Arc flash accidents, a number of the Hiroshima Maidens survived despite their close proximity to the explosion and in a range where the flash-fire of their customary Japanese summer attire, made of thin kimono cloth, was near instantaneous.

[91] While not designed for those faced with low-yield neutron bombs or for those who are, in general, so close to the nuclear fireball that prompt/initial radiation would be life-threatening in the short-medium term, ducking and covering would nevertheless slightly reduce exposure to the initial gamma rays, specifically the portion emitted after the first flash of visible light.

[92] The initial gamma rays are defined as those emitted from the fireball & following mushroom cloud which can reach personnel on the ground for a total of approximately 1 minute, at which point the intensity of the radiation has diminished and the atmosphere itself is thick enough to act as full shielding.

[103][104] Putting aside the possibility of the detonation occurring during an already established heavy rain-storm, the formation of this life-threatening "delayed nuclear radiation" manifests only when the altitude, or "height of burst" of the explosion, is such that both the fireball and the buoyant updrafts it creates, sufficiently heats and lifts the soil that was below it into the core of the mushroom cloud.

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[116] and due to complications in the treatment of the ship's radio operator months after the exposure, resulted in his death.

[118] 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.

[120] A notable comparison to underline this is found when one compares the 50 megaton air-burst Tsar Bomba, which produced no concentrated local/early fallout and thus no known deaths from radiation, with the surface burst of the 15 megaton Castle Bravo, which in comparison, due to the local fallout produced, was implicated in the death of 1 of 23 crew on the Lucky Dragon and made the entire Bikini Atoll unfit for further nuclear testing until enough time elapsed and the intensity of the radiation field had decayed to acceptable levels.

[136] Indeed, death and injury from local fallout is regarded by experts as the most preventable of all the effects of a nuclear detonation, being simply dependent on if personnel know how to identify an adequate shelter when they see one and enter one quickly, with the number of potential people saved being cited as in the hundreds of thousands.

[139][141] In 2009 to 2013 a further iteration on sheltering-in-place was made to determine the optimal improvised fallout-shelter-residence-times following a nuclear detonation, with computer analysis, and including a summary of prior studies and guidance.

[142][143][144][145] However, although this would be effective in cases where the initial building protection factor is less than about 10, it requires a high degree of individual situational awareness that may be optimistic to assume following the shock of a nuclear detonation.

When armed with this prediction they would then begin attempting to corroborate this with readings from radiation survey meter equipment that would fly over close to the ground in the affected area by means of helicopter or drone (UAV) aircraft on material intelligence gathering missions,[146] which would also follow within tens of minutes to at most hours after the detonation.

However even at that time, this assumption was shown to be misled, as scientifically detailed in areas including the 1988 book Would the Insects Inherit the Earth and Other Subjects of Concern to Those Who Worry About Nuclear War.

Cold War continuity of government planners and civil defense organizations in general have always had this disruption, or "nuclear famine" issue in mind, as widespread infrastructure destruction producing starvation conditions was also seen during and after WWII.

[167] Although less of a hazard than external exposure, internal decontamination, that may be required after assessment in a whole-body counting session, in the long term may, as is now, be conducted with binding-and-excretion promoting chelation therapy, with ammonium-ferric-hexacyano-ferrate (AFCF)/"Giese salt",[164] Radiogardase and DPTA all proven effective.

[181][182] Researchers at the American Chemical Society have further suggested that aquaponics[183] would be an ideal socially-acceptable solution in the post-contamination environment, as it does not use soil to grow fish and vegetables,[184] thus completely alleviating the radiophobia surrounding food that always follows long-lived contamination incidents.

Others who have approached the food problem from a far more extreme view, assuming far worse events such as comet impacts (as discussed in the book Feeding Everyone No Matter What) have suggested: natural-gas-digesting bacteria, the most well known being methylococcus capsulatus, which is presently used as a feed in fish farming;[185] bark bread, a long-standing famine food using the edible inner bark of trees (once a part of Scandinavian history during the Little Ice Age); and the expansion of leaf protein concentrate and larger scale wood digesting fungiculture for fungal protein, with the most common of which being shiitake mushrooms and honey fungi, as they do not need sunlight or soil to grow.

In an earthquake, which are generally of a natural tectonic plate origin (although they can be artificially generated by the detonation of a nuclear explosive device in which sufficient energy is transmitted into the ground, with an extreme case to serve as an example of this phenomenon being the Operation Grommet Cannikin test of the 5 megaton W71 warhead exploded deep underground on Amchitka Island in 1971, which produced a seismic shock quake of 7.0 on the Richter magnitude scale) people are encouraged, regardless of the cause of the quake, to "drop, cover and hold on": to get underneath a piece of furniture, cover their heads and hold on to the furniture.