Remain in the most protective location (basement or center of a large building) for the first 24 hours unless threatened by an immediate hazard (e.g., fire, gas leak, building collapse, or serious injury) or informed by authorities that it is safe to leave.
THE NEXT 48 HOURS
You have been sheltered because of the potential for dangerous levels of radiation in the first 24 hours following a nuclear detonation. After 24 hours, outdoor radiation levels will have fallen significantly but may still warrant protective measures in your area.
At a distance of 20-25 miles downwind, a lethal radiation dose (600 rads) would be accumulated by a person who did not find shelter within 25 minutes after the time the fallout began. At a distance of 40-45 miles, a person would have at most 3 hours after the fallout began to find shelter.
The best location is in the half of the building farthest from the blast, in a room with no windows. But, "even in the front room facing the explosion, one can be safe from the high airspeeds if positioned at the corners of the wall facing the blast," Kokkinakis told Insider.
Seek shelter indoors, preferably underground and in a brick or concrete building, per the Red Cross and FEMA. Go as far underground as possible, per the Red Cross and FEMA. If that's not possible, try to stay in the center of the building, for example in a stairwell.
The only good news is that research has shown that Australia and New Zealand are among the best places in the world to survive a nuclear apocalypse. Australia scored well as it has a good infrastructure, a huge energy surplus, high health security and abundant food supplies.
Beta particles travel appreciable distances in air, but can be reduced or stopped by a layer of clothing, thin sheet of plastic or a thin sheet of aluminum foil. Several feet of concrete or a thin sheet of a few inches of lead may be required to stop the more energetic gamma rays.
A 1,000-kiloton nuclear blast might produce third-degree burns up to 5 miles away, second-degree burns up to 6 miles away, and first-degree burns up to 7 miles away, according to one estimate from AsapScience. People up to 53 miles away could also experience temporary blindness.
Here's a fun fact that's nice to know, but we hope you never, ever need to use: the best place to hide during a nuclear bomb explosion is in a strong, concrete structure, researchers at the University of Nicosia in Cyprus say in a January 2023 study published in the journal Physics of Fluids.
Scientists have recently revealed that Australia and New Zealand are best placed to survive a nuclear apocalypse and help reboot collapsed human civilisation. The study, published in the journal Risk Analysis. These countries include not just Australia and New Zealand, but also Iceland, the Solomon Islands and Vanuatu.
If an attack warning is issued, take cover as quickly as you can, below ground if possible, and stay there unless directed otherwise by authorities. Find the nearest building, preferably built of brick or concrete, and go inside to avoid any radioactive material outside.
However, lack of apparent fallout does not suggest lack of radiation. Continued radiation monitoring is required. Fallout decays rapidly 7-10 Rule: For every sevenfold increase in time after detonation, there is a tenfold decrease in the radiation rate.
In a typical air burst, where the blast range is maximized to produce the greatest range of severe damage, i.e. the greatest range that ~10 psi (69 kPa) of pressure is extended over, is a GR/ground range of 0.4 km for 1 kiloton (kt) of TNT yield; 1.9 km for 100 kt; and 8.6 km for 10 megatons (Mt) of TNT.
Removing the outer layer of clothing can remove up to 90 percent of radioactive material. Take a shower or wash with soap and water to remove fallout from any skin or hair that was not covered. If you cannot wash or shower, use a wipe or clean wet cloth to wipe any skin or hair that was not covered.
But the vast majority of the human population would suffer extremely unpleasant deaths from burns, radiation and starvation, and human civilization would likely collapse entirely.
Because radioactive materials settle on the outer walls and roof. In a multi-story building made of brick or concrete, the most secure are closed rooms on the middle floors. The most reliable shelter is the basement. Underground shelters can protect not only from radiation, but also from debris and blast waves.
In a study published in Physics of Fluids, scientists simulated an atomic bomb explosion to determine the best and worst places to be in a concrete-reinforced building during such an event. The safest place: the corners of a room, author Ioannis Kokkinakis of Cyprus' University of Nicosia said in a statement.
The study published in the journal Risk Analysis describes Australia, New Zealand, Iceland, Solomon Islands and Vanuatu as the island countries most capable of producing enough food for their populations after an “abrupt sunlight‐reducing catastrophe” such as a nuclear war, super volcano or asteroid strike.
For a 1 KT device, radiation exposure from fallout within the first hour after the blast could cause 50% mortality from radiation exposure, to individuals without medical intervention, for approximately 3.5 miles (5500 m) downwind of the event.
This direct radiation is produced in the weapon's nuclear reactions themselves, and lasts well under a second. Lethal direct radiation extends nearly a mile from a 10-kiloton explosion.
You'll only have about fifteen minutes to seek sufficient cover, but radiation will die down to acceptable levels in most of the blast area after just a few days. Note that fallout is at its absolute worst in the first 72 hours, so it's crucial to evacuate immediately or stay sheltered.
Shielding: Barriers of lead, concrete, or water provide protection from penetrating gamma rays. Gamma rays can pass completely through the human body; as they pass through, they can cause damage to tissue and DNA.
Lead has long been considered "the element of choice" for radiation shielding due to its attenuating properties. Lead is a corrosion-resistive and malleable metal. Lead's high density (11.34 grams per cubic centimeter) makes it an effective barrier against X-ray and gamma-ray radiation.
In December 2001, the federal Food and Drug Administration (FDA) said if there was a radiation emergency, people should take a drug that would help protect them from thyroid cancer. This drug is called potassium iodide (KI). The New York State Health Department agrees.