How to survive nuclear war after a bomb is dropped: what to do, how to prepare

• As Russia escalates its nuclear threats, the fear of a nuclear bomb is real.
• If a nuclear attack were headed toward the US, residents would have fewer than 30 minutes to prepare.
• Actions immediately following a nuclear bomb blast amid fallout could help you survive.

Nuclear war has been a growing threat ever since the Manhattan Project detonated the first atom bomb in the New Mexico desert 78 years ago.

The development of that first nuclear weapon, an effort led by J. Robert Oppenheimer, is the subject of the new Christopher Nolan film, "Oppenheimer," which hit theaters on Friday. Even though the movie takes places decades ago, its message is timely.

"It's safe to say we're in the midst of an incredibly dangerous moment, where the use of nuclear weapons seems more possible now than at any time since the end of the Cold War," Stephen Miles, president of the activist organization Win Without War, said in a panel about the movie on Monday.

Since Russia launched its invasion of Ukraine, President Vladimir Putin has made repeated threats about resorting to nuclear force. He escalated these threats in June with the announcement that Russia was moving tactical nuclear weapons into Belarus.

US leadership has said it has no indication that Russia plans to use these weapons. But President Joe Biden has raised the possibility of a nightmare scenario: an all-out nuclear war. 

Some expert observers see Putin's rhetoric as an attempt to scare away Western support for Ukraine, while others take it as a significant increase in the risk of nuclear attacks.

A nuclear attack remains highly unlikely, but it's not out of the question, experts say.

How much time Americans would have between a nuclear alert and strike

If your city was under attack, you'd likely receive a Wireless Emergency Alert (WEA) text on your cell phone stating that missiles were on the way and to seek shelter immediately. 

The Emergency Alert System (EAS) would also send out the same alert message as the WEA across all types of television and radio broadcasts, including satellite, cable, and wireless systems. On top of that, the President may choose to send out a "Presidential Alert" to cell phones nationwide.

Russia's nuclear arsenal is capable of striking just about anywhere on the planet. Were Russia to launch a nuclear-armed intercontinental ballistic missile at the US, residents would have roughly 30 minutes, or less, to find shelter, assuming they were immediately warned of the attack. Some weapons, such as submarine-launched missiles, could potentially have shorter delivery times. 

"In theory you could park a submarine closer to North America, thereby lessening the warning and flight time," said Brian J. Morra, a former Air Force intelligence officer, a retired senior executive in the aerospace and defense industry, and author.

If Russia launched a weapon from international waters just off the East Coast, people in cities like New York, Boston, and Washington, DC, might have just 10 to 15 minutes to prepare.

"You wouldn't even have time to go get your kids from school," Irwin Redlener, a public-health expert at Columbia University who specializes in disaster preparedness, told Insider last year.

Arguably, the American public is not as prepared or educated on what to do in the event of a nuclear attack as Americans were during the Cold War, when stocked fallout shelters, nuclear drills, and air raid sirens were in place across the nation. So here's a minute-by-minute guide to help.

What to do after a nuclear attack

The minutes to hours after a nuclear blast are a critical window. The potential for radiation exposure decreases 55% an hour after an explosion and 80% after 24 hours, according to the Johns Hopkins Center for Health Security.

Immediate actions during those first few hours, like covering your eyes or hunkering down in an indoor shelter, could mitigate your risk of death or serious injury. Here's how to protect yourself in a worst-case scenario.

First 30 minutes: Avert your eyes and shield your face 

The US doesn't have a sufficient warning system for nuclear threats, Redlener said.

Hawaii learned this lesson in 2018, when the Hawaii Emergency Management Agency sent out an erroneous push alert to people's smartphones, warning of an inbound ballistic-missile threat.

"Seek immediate shelter. This is not a drill," the warning read. An employee at the agency had sent the alert by mistake.

"It caused chaos," Redlener said, adding: "Some people just totally ignored it, and some people went into panic mode and were jumping down sewer drains with their children."

Redlener said the best way to learn of an impending nuclear attack would probably be TV or radio. Those without immediate access to news reports could hear sirens, he said, but the noise might be confusing. By the time you googled the sirens or called the police department, your time would have run out, he said.

The best course of action is simply to avert your eyes. When a nuclear bomb strikes, it sets off a flash of light and a giant orange fireball. A 1-megaton bomb (about 80 times larger than the "Little Boy" atomic bomb dropped on Hiroshima, Japan) could temporarily blind people up to 13 miles away on a clear day and up to 53 miles away on a clear night.

The Centers for Disease Control and Prevention also recommends dropping to the ground with your face down and your hands tucked under your body to protect from flying debris or sweltering heat that could burn your skin. If you have a scarf or handkerchief, cover your nose and mouth.

But make sure to keep your mouth open, so your eardrums don't burst from pressure. Research also suggests that if you're in an above-ground building, avoid narrow hallways and doorways, which can act like a windtunnel, accelerating the detonation's shockwaves to dangerous, bone-crushing pressures. Instead, seek shelter along walls in large, open spaces and avoid rooms with windows, if you can.

First 45 minutes: Seek shelter indoors away from windows

A single nuclear weapon could result in tens of thousands, if not hundreds of thousands, of immediate deaths in a major city like New York or Washington. The number of casualties depends on the size of the weapon, where it's detonated, and how many people are upwind of the blast.

Survivors of a nuclear attack would have about 15 minutes before sandlike radioactive particles, known as nuclear fallout, reached the ground. Exposure to fallout can result in radiation poisoning, which can damage the body's cells and prove fatal.

People should ideally look for shelter in the opposite direction of fallen buildings.

"You'd want to go in the direction away from the wind," Redlener said, adding: "Get as far away as you can in the next 10 to 15 minutes, and then immediately seek shelter before the radiation cloud descends."

The best shelters are buildings like schools or offices with few to no windows and a basement for camping out. If there aren't sturdy buildings nearby, it's still better to be indoors than outside.

If you take cover in a multistory building, choose a central location and steer clear of the top and bottom floors. If the building has windows, stand in the center of a room. Shock waves can shatter windows up to 10 miles away from an explosion, resulting in flying glass that could injure people nearby.

First 24 hours: Rinse off in the shower and stay inside 

The hours after a blast are critical for reducing radiation exposure.

Doctors can often treat radiation damage with substances such as potassium iodide, though "there are certain dose levels that you can't do anything about," Kathryn Higley, a professor of nuclear science at Oregon State University, told Insider. 

But in a disaster scenario, there may not be enough physicians or hospital beds to care for everyone.

"There are not enough empty burn beds in all of the United States to deal with even a single nuclear attack on one city in the US," Tara Drozdenko, the director of the Union of Concerned Scientists' Global Security Program, told Insider.

People who were outside during an explosion should shower as soon as possible, making sure the water is warm and soap is applied gently. Scrubbing too hard could break your skin, which acts as a natural protective barrier. You should also cover any cuts or abrasions while rinsing off. Complete these same steps for pets, too.

Don't use conditioner, body lotion, or face cream after exposure to a nuclear blast, since these products can bind to radioactive particles and trap them in your skin and hair.

Blow your nose and wipe your ears and eyelids, since debris could get stuck in these places. The CDC also recommends sealing outer layers of clothing in a plastic bag, along with any tissues or cloths used to wipe your body or face.

It's safe to consume food from sealed containers such as packages, bottles, or cans, according to the CDC. You can also eat items from your pantry or refrigerator, as long as you wipe off containers, cookware, counters, and utensils. But anything left uncovered, such as fruits or veggies from a garden, would be unsafe to eat.

Unless you're told to go outside, it's best to stay put until the risk of contamination has gone down. The US Department of Health and Human Services recommends staying indoors for at least 24 hours after a nuclear explosion.

First 7 days: Listen to the radio or television for next steps

The World Health Organization recommends listening to the local radio for information and advice on next steps. Your cell phone, television, and internet probably won't work, but battery-powered and hand-crank radios should.

Over the radio, authorities may advise you to stay put or issue an evacuation to a safer area. This is where you'll also likely learn about available medical aid, if you or someone with you, is sick.

If you venture outside, know that nuclear fallout will be raining from the sky. Most fallout from a nuclear blast takes about a week to return to the ground. 

To reduce exposure, cover your mouth and nose with a damp cloth when you go outside and make sure you don't have any exposed open wounds. Also, avoid any food that's directly exposed to open air like fresh produce or open water supplies.

Ultimately, the best thing you can do is remain indoors for the first week while the majority of nuclear fallout settles back down to the ground.