Nuclear experts say it's not out of the question that a nuclear bomb could be used in the US.

The US Federal Emergency Management Agency has an emergency strategy for 15 disaster scenarios, including a nuclear attack in a large metropolitan area. First responders, evacuees, and victims of radiation exposure are some of the people the agency wants to help.

FEMA advises everyday citizens to get inside, stay inside, and keep an eye on the news.

According to Redlener, the federal guidelines aren't enough to prepare a city for a nuclear attack.

There isn't a single jurisdiction in America that has a plan in place to deal with a nuclear detonation.

New York, Chicago, Houston, Los Angeles, San Francisco, and Washington, DC are some of the cities that Redlener thinks are most likely to be hit by a nuclear attack. Critical infrastructure such as energy plants, financial hubs, government facilities, and wireless transmission systems are located in these cities, which are some of the largest and densest in the country.

Most of the websites that inform citizens about what to do in a crisis do not mention a nuclear attack. If a bomb were to hit one of those cities, it would be hard for residents to know how to protect themselves.

Redlener said that it wouldn't be the end of life. It would be a catastrophe with many unknown and cascading consequences.

Cities might struggle to provide emergency services after a nuclear strike

Nuclear bombs can create clouds of dust and radioactive particles in the air. Radiation poisoning can be caused by exposure to this fallout and can be fatal.

A person's response to an explosion could be the difference between life and death, because the debris takes at least 15 minutes to reach ground level. The center or basement of a brick steel or concrete building is the best place for people to seek refuge.

Brooke Buddemeier is a health physicist at the Lawrence Livermore National Laboratory. Emergency managers are advised about how to protect their populations.

He said that if we could just get people inside, we could greatly reduce their exposure.

A single nuclear explosion from North Korea is the most important scenario to prepare for. He said that North Korean missiles could soon be able to reach cities along the West Coast.

A nuclear device built, purchased, or stolen by a terrorist organization is one of the possible sources of an attack. According to the US Department of Homeland Security, "Tier 1 areas" are places where a terrorist attack would yield the most destruction.

Redlener stated that there is no safe city. In New York City, the detonation of a Hiroshima-sized bomb, or even one a little smaller, could have tens of thousands of deaths and hundreds of thousands of injuries.

New York Nuclear Attack
An estimate of the damage from a 15-kiloton blast in New York City. Thermal radiation can result in third-degree burns, while an air blast could kill people and topple residential buildings.
Nukemap 2.65/Alex Wellerstein/Google Earth/Business Insider

The estimates are higher. According to Alex Wellerstein, a nuclear-weapons historian at the Stevens Institute of Technology, a 15- kiloton explosion in New York City would cause more than 225,000 deaths and 600,000 injuries.

Not a single hospital bed would be available in the entire state of New York.

Almost all of New York state's hospital beds are occupied.

He was concerned about what might happen to emergency responders.

Is the National Guard going to be ordered to go into highly radioactive areas? He asked if we would be getting bus drivers to take people to safety. "Strategic or tactical responses are fraught with problems."

Big cities don't have designated fallout shelters

During the height of the Cold War, the US launched a program to keep people safe in the event of a nuclear detonation. The purpose of the shelters was to protect people from radiation and not the blast.

The federal government paid for food and supplies for those shelters. Up to 11 million people were protected by New York City's 18,000 fallout shelters when the program ended.

New york fallout shelter.JPG
A sign for a nuclear fallout shelter on a building in Brooklyn.
Brendan McDermid/Reuters

The yellow signs that used to mark these shelters were removed in order to make them seem like they were still active.

Major cities like New York and San Francisco are in need of more affordable housing which makes it difficult for city officials to reserve space for food and medical supplies.

Is it possible for a public official to keep buildings intact when the real-estate market is so tight? Redlener made a statement.

'This is part of our 21st-century reality'

Many city authorities worry that offering nuclear-explosion response plans could cause panic.

If the public knew what the mayor knew in the event of a nuclear attack, they would be afraid, he said.

It doesn't have to be frightening to educate the public.

He said that "Get inside, stay inside, stay tuning" works. I like to call it stop, drop, and roll. That's what you should do if your clothes catch on fire. It doesn't make you afraid of fire, but it does give you the chance to save your life.

Both experts agree that for a city to be prepared for a nuclear attack, it must acknowledge that it is possible.

Redlener said that this is part of the 21st century reality. I apologized to my children and grandsons for leaving the world in such a bad state, but it is what it is now.