New York City released a public service announcement in July 2022 outlining actions to take in the event of a nuclear attack. The randomness of the message, along with the laid-back demeanor of the presenter, left many perplexed and questioning its usefulness.

1. Seek shelter.
2. Remain indoors.
3. Stay updated via media.

I found myself pondering, “What would actually happen if a nuclear bomb detonated in NYC? How effective would this video really be?”

After taking some prescribed medication, I set out to explore the answer. I might not have the local knowledge of a true New Yorker—having never set foot there—but I’ll give it a shot anyway. Who better to discuss the devastation of a city than someone with no emotional ties to it?

I promise I won't plunge you into a hypothetical nuclear disaster without some context. We'll still dive into that scenario, but let's create some atmosphere first.

Imagine this:

It's a bright, sunny Tuesday in New York City. You’re en route to lunch with that charming person you met on Hinge. You opted for lunch because you’ve been eager to try that restaurant’s special. When you arrive, your date looks even more appealing in person.

Given the lovely weather, you choose a patio table. Your meal arrives, and as a gentle breeze flutters the napkins, one takes flight. You reach for it and tumble from your chair—it's a lighthearted moment that both of you will cherish for years to come.

Or at least you would, if a nuclear explosion didn’t occur at that very moment.

How’s that for ambiance?

I hope you enjoyed that. From here on out, it's all about the numbers. My primary sources for this information are listed at the end of this article.

So, what happens when a nuclear bomb strikes a city? Typically, if one bomb goes off, more are likely to follow. However, for simplicity's sake, let’s assume just one detonates.

But realistically, if one goes off, others will likely follow.

Nuclear explosions are quantified in kilotons and megatons. A megaton equals one million tons of TNT. The most powerful nuclear device ever detonated was the Soviet Union's Tsar Bomba, boasting an explosive yield of 50 megatons—equivalent to 50 million tons of TNT (for context, the Soviet Union is now known as Russia).

A kiloton equals 1,000 tons of TNT; for example, Little Boy had a yield of 15 kilotons (15,000 tons of TNT).

Nuclear weapons are designed to explode at specific altitudes to optimize effects based on the target. Higher altitudes are generally for civilian targets (strategic), while lower altitudes are for military targets (tactical). While strategic and tactical refer more to usage than design, tactical weapons often have lower yields and shorter ranges.

The height of detonation determines whether it results in an air burst or a surface burst. The two are distinct in the damage they cause. Both types technically explode in the air, but the key difference lies in whether the fireball significantly interacts with the ground.

An air burst occurs when the fireball doesn't make substantial ground contact, leading to minimal localized radiation (fallout). The iconic mushroom cloud arises from the condensation of water droplets rather than debris.

Air bursts generate high overpressure across broader areas and intensify thermal radiation. Overpressure is the air pressure exceeding normal sea-level conditions, measured in pounds per square inch (psi), and is what gives a bomb its destructive force.

• An overpressure of 0.5 psi shatters windows.
• An overpressure of 2 psi demolishes wooden structures.
• An overpressure of 8 psi collapses brick walls.

Typically, urban areas are obliterated with an overpressure of 5 psi.

Surface bursts also generate overpressure, but the crucial difference is nuclear fallout. Following the explosion, radioactive particles—including fission material, irradiated soil, and debris—are propelled into the atmosphere. Wind conditions heavily influence the dispersal of this radioactive fallout, which can travel vast distances, even hundreds of miles.

Now that the technical details are out of the way, let’s return to your date. A nuclear explosion has just occurred.

What now?

I’ll delve deeper into the numbers. If you've made it this far, perhaps you're ready to continue.