I usually try to have fun at social gatherings, but almost inevitably someone who knows what I do for my “day job” asks me about nuclear weapons. “What’s up with North Korea?” “Is this Iran deal a good thing?” “Russia’s developing all these new weapons, what gives?!” “Looks like India and Pakistan might go to war, and they both have nukes!” “Geez, I didn’t know there were nuclear missile submarines in Seattle!”

Often, this leads to conversations about how bad a nuclear bomb, or even a nuclear war, would be. And this is when I start to be “that guy” that people at the party avoid, because the truth is that—even as we tend to focus on wildfires, earthquakes, and climate change—nuclear weapons still pose cataclysmic threats: They are a buzzkill. But—as folks at parties often realize too late—I passionately believe that the better we understand these weapons, the less likelihood there is that they will be used. And for this reason, I proceed to describe in detail the horrors that nukes pose.

So, in the same spirit, I want to help you imagine a run-of-the-mill nuclear blast in the place where you spend most of your days—maybe after a morning coffee on the way to work.

Destruction from a nuclear explosion comes in three main types: blast, heat, and radiation. Generally speaking, the blast causes about half of the damage, and heat from the detonation causes another third or so. To get a sense of what nuclear scale and speed really means in your daily life, consider what happened when the U.S. government did tests in Nevada in the 1950s. In one fairly routine test, a 16-kiloton “device” was exploded from a tower about 50 feet high. Within 2.5 seconds a house more than half a mile away underwent three distinct things: It first caught fire from the heat wave, then the fire was blown out by winds over 400 mph, and finally the entire structure disintegrated from the trailing end of the blast wave.

Now think about the café where you get your morning coffee: Within 2.5 seconds everything 12 football fields away is gone.

But nuclear bombs aren’t just big versions of regular bombs. They are in a category all by themselves due to a third feature that makes them particularly insidious—radiation. Because nuclear bombs harness—or rather let loose—energy from the fission and fusion of atomic nuclei, they release a witches’ brew of radioactive particles. This radiation “sticks” to the dirt, dust, and shattered materials from the explosion itself, creating fallout. So now you have tons of stuff blowing in the wind that has become radioactive. Some of these radionuclides only last seconds, while others last months and years. All of it is harmful to life—some immediately lethal, some corrosive over time.

To be clear, only a small percentage of deaths would be due to what is called “prompt radiation” immediately after the bomb goes off—simply because anyone close enough to get a lethal dose of radiation would more likely be killed by blast or heat first. It is the longer-lasting radioactive elements that cause an array of health problems over time and that are frankly not very well understood.

A macabre quip about nuclear war is that the dead would be better off than the survivors. This is because those left alive would face a world unlike any we have known. Water would be contaminated, vegetation compromised, animals rendered inedible, and air would carry radiation that could and would make us sick and die. And these conditions would prevail not just near the blasts, but miles and miles away for weeks, months, and years.

Before I try to leave you with some hope and ideas about how we can all avoid this fate, let’s take a closer look at a theoretical event. There is a wonderful, scary, sanitized, and essential website called Nukemap that provides a comprehensive array of locations, bombs, and the resulting effects and casualties that would likely result from an explosion. It’s like Expedia for those of us who are curious about the realities of nuclear weapons. Pick a zip code or landmark, choose your preferred “mode” or bomb size, what “accessories” you want (deaths, radiation circles, blast radius) and hit “Detonate.” Voilà! You get nice, clean rings of death; oh, and a ticker that counts up the dead and injured. Gory? Yes. A downer at parties? For sure. But it’s important to have something like this to remind us of the magnitude of the threat.

My last time on the site, I picked Washington, D.C., because the White House is about a mile from the U.S. Capitol. And that’s a good unit of measurement when dealing with nuclear explosions. Let’s say a 150-kiloton bomb—much larger than the one dropped on Hiroshima, but kind of a welterweight by today’s standards— falls on the Washington Monument. Within the first few seconds, an intensely hot fireball would incinerate everything within a quarter-mile radius—glancing the Jefferson Memorial, reaching nearly to the White House, taking out the World War II Memorial, and some federal buildings like the Department of Agriculture, and, on Independence Avenue, just touching the Department of Energy, which builds our nuclear weapons.

Within the next few seconds the air blast wave would reach about 2.25 miles. At this distance the “overpressure” or extra force above normal atmospheric pressure would be five pounds per square inch. As Nukemap describes, “At 5psi overpressure, most residential buildings collapse, injuries are universal, fatalities are widespread.” Any friends or colleagues in Dupont Circle, Georgetown, Capitol Hill, or even Rosslyn in Virginia? Likely not anymore. Oh, and the Pentagon itself is well within this circle too.

Beyond those two zones, thermal effects from the heat (that is, heat outside the fireball itself) would extend out some 3.25 miles—well past the U.S. Capitol, George Washington and Gallaudet Universities, Reagan National Airport, and Union Station. Within this zone, Nukemap says third-degree burns are universal and they “extend throughout the layers of the skin and are often painless because they destroy the pain nerves. They can cause severe scarring or disablement, and can require amputation.”

The other “data point” of note is the body count. In the initial blast and heat, 243,000 people would die, and about 460,000 people would be injured. Think about that: nearly half a million people with severe burns, broken bones, and internal injuries, bleeding, blinded, coughing, unable to move, and nauseated from radiation. Where would they go to be treated? Who would treat them? After all, doctors and ambulance drivers are human beings too, they’d be just as likely to be dead or incapacitated. How could the regional infrastructure possibly handle this size of disaster adequately?

While we’re at it, what would broader society look like in the hours after such a calamity? If you remember the days after 9/11, recall the surreal feeling of no airline travel, no international travel, and a de facto state of martial law. The hours and days after a nuclear blast, or many blasts, is anyone’s guess. Alive or not, there would be utter chaos, utter authoritarianism, or some of both. One thing is near certain: It would not resemble the “Pleasantville” view of nuclear preparedness the government, and industry, used to purvey in ads during the early days of the Cold War.

Why do we need reminding of all this now? Because a new generation needs to know these truths. It used to be that the awesome and awful nature of nuclear threats paralyzed people. Such huge power, the shroud of secrecy surrounding nuclear weapons, and the high degree of technical knowledge required to even talk about it, served to reserve debates and decision-making on the subjects for elites—elite countries, elite officials, and “experts.” Most of us had nothing to do with the conversation.

But nukes are not an elite issue—nor one we can afford to leave to experts. These weapons threaten every single one of us, and you don’t need a specialized degree or top secret clearance to take part in the conversation about avoiding the worst. The time has come to encourage everyone to take part.

One example of the impact citizens can make on this issue is the International Campaign to Abolish Nuclear Weapons, known by the empowering name of ICAN. Winner of the 2017 Nobel Peace Prize, ICAN is a global grassroots movement of hundreds of organizations and thousands of individuals with one common goal—to make nuclear weapons illegal. Some criticize this approach as naïve and merely symbolic. But ICAN has succeeded in achieving formal adoption of their proposed global treaty at the United Nations and has made progress in gathering national ratifications that would make the treaty legally binding worldwide. In fact, it’s nearly halfway there, with some 22 nations of the 50 needed to make it so.

Regular people also can connect to the subject through storytelling. The 1983 television movie The Day After not only galvanized a significant number of Americans around the threat of nuclear war, but also may have changed the mind, and heart, of a president. Credible sources have stated that, before his historic summit meeting with Soviet Premier Mikhail Gorbachev, President Ronald Reagan watched The Day After. He asked his national security advisors if the horror he saw, and the utter inability of the government to respond, was true. Yes, they said. This realization convinced him to suggest the complete elimination of nuclear weapons between the U.S. and Soviet Union. It nearly happened. It’s worth trying again.

Each of us, sufficiently motivated and with just a bit of collaboration, can build an impressive, effective, even irresistible force toward eliminating nuclear weapons risks. In the age of Twitter, Facebook, and Instagram, when one voice can leverage millions, asking, “but what can one person do?” seems out of touch. And what could be more sufficiently motivating than the knowledge that, in the time it takes a barista to pour your latte, several square miles and tens of thousands of human beings could cease to exist?