Most Dangerous Places in an EMP: What the Evidence Says

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Most “dangerous places in an EMP” lists repeat the same frightening picture: jets falling out of the sky, every car since the 1960s dead on the highway, nuclear plants melting down and people trapped in elevators for days. An earlier version of this page did too. This version checks each of those places against what was actually tested. The main source is the federal EMP Commission’s 2008 report on critical national infrastructures, which exposed real cars and trucks to simulated EMP. Official safety guidance supplies the rest.

Short version: the realistic dangers are crashes when some running vehicles stall and traffic signals fail, a long wait in a stuck elevator, and medical equipment losing power. The fix for an elevator is to stay put and call for help, not to climb out. The place you are most likely to be is home, and that is where preparation pays off: water, light, a battery radio, and a plan for any medicine or device that needs electricity.

Each place at a glance

This table sums up what the evidence supports for each place and what to do there. The sections below explain each row, the popular claim it corrects, and the limits of the evidence.

On the road: will an EMP stop your car?

This is the claim with the best evidence. The commission tested 37 cars, model years 1986 to 2002, in an EMP simulator. Field strength was raised step by step up to the simulator’s limit of about 50 kV/m, and testing on a car stopped at the first unusual response. The results (report pages 115 and 116):

• Switched-off cars: “No effects were subsequently observed in those automobiles that were not turned on during EMP exposure.”
• Running cars: the engines of three stopped at about 30 kV/m or above. The report says these cars “would glide to a stop and require the driver to restart them.” One car’s dashboard electronics were damaged and needed repair.
• Nuisance effects: 25 cars showed things like blinking dashboard lights that did not need the driver to do anything. Eight showed no response at all.
• Trucks: 18 trucks, model years 1991 to 2003, from pickups to diesel tractors. None that were switched off were affected. Three running trucks stalled: two restarted immediately and one had to be towed for repair.

From these results the commission expected few car effects below 25 kV/m. Above that, it expected roughly 10 percent or more of cars to suffer serious effects such as stalling, and about 15 percent or more of trucks. The danger it highlighted was not a dead fleet. It was “triggered crashes that damage many more vehicles than are damaged by the EMP.”

Traffic signals are the other road hazard. The commission’s tests found controllers starting to malfunction at only a few kV/m. Lights skipped yellow, ran wrong cycles, stuck red on side streets or went to all-way flashing. It reported that conflicting greens did not occur, and that these failures would disrupt traffic less than a power outage that leaves signals completely dark.

Limits: these were 1986–2003 vehicles. Today’s cars carry more electronics and also more interference shielding, and no comparable public test of current models exists. Nobody can tell you whether your particular car would keep running. Claims that a specific “EMP-proof” vehicle or add-on device guarantees it go beyond any public evidence.

What to do if you are driving

1. If the engine dies, switch on your hazard lights (if they work) and steer to the shoulder while you still have momentum. Power steering and brake assist may be reduced, so expect heavier steering and braking.
2. Once stopped and safe, try a normal restart. In the tests, most stalled vehicles started again.
3. Approach any dark, flashing or erratic signal slowly and be ready to stop. Expect other drivers to be confused. Your state’s rule for dark signals (often to treat them as an all-way stop) still applies.
4. Give stalled vehicles room. The commission’s main concern was crashes, not the vehicles themselves.

The “old 1960s truck” and spare-parts advice

The tests don’t support buying an older vehicle and storing its ignition parts in a Faraday cage. Parked cars that were switched off showed no effects, and most stalled running cars restarted. Older, simpler vehicles may well be less susceptible, but they weren’t part of the tests. The commission said what limits road travel after a large event is mainly fuel and electric power, because gas pumps need electricity. A sensible plan is to keep your tank reasonably full and keep a basic car kit, not to rebuild a vintage truck. Our car emergency kit checklist covers the roadside and weather basics.

In the air: would planes fall out of the sky?

The numbers this page used to quote, about 4,000 flights and hundreds of thousands of deaths in the first hour, were attributed to the author of an EMP novel. They don’t come from testing. The commission did not test aircraft. Its assessment came from discussions with Boeing’s electromagnetic-effects engineers (report pages 123 and 124), and its conclusion is genuinely uncertain:

• Airliners are qualified against lightning, the natural environment most like EMP. Flight-critical boxes must withstand at least twice the stress expected to reach them.
• Aircraft designed before the Boeing 777 kept mechanical or hydraulic links to the control surfaces. Newer fly-by-wire designs use up to four levels of redundancy, including analog backups.
• Even so, those qualification tests don’t cover EMP. In the commission’s words: “we cannot confirm safety of flight following EMP exposure.” Elsewhere it says lightning margins “may provide flight safety” but that crashes cannot be ruled out, especially if air traffic control is damaged.
• It expected all aircraft to be directed to land immediately.

So the honest answer is unknown, with significant engineering protection, not certain disaster. Passengers have nothing specific to prepare: keep your seatbelt fastened and follow the crew. The bigger practical effect is on travel afterwards. The commission warned that restoring the full air traffic control system could take months or longer, so a family plan shouldn’t depend on flying home.

In an elevator: stay in the car

This is where the earlier version of this page gave genuinely dangerous advice. It told readers to climb out through the roof hatch and into the shaft. The commission does expect that “people trapped on subways and in elevators will require timely rescue,” because any widespread outage stops elevators. The official advice on what to do inside is consistent, and it is the opposite of climbing out:

• The New York City Department of Buildings’ elevator safety rules: ring the alarm, wait without prying the doors open, and “never attempt to exit a stalled elevator without the help of the building management” or emergency personnel.
• Elevator maker Otis’s five steps:
  • don’t leave the cab unless a certified technician or the fire department clears you
  • use the emergency button, intercom or phone
  • keep away from the doors
  • only qualified people should carry out a rescue

  Otis also notes that elevator cabs have air circulation openings, so you will not run out of air.

A car that is stopped between floors can move without warning, and the shaft has drops and moving equipment. That is why these rules reserve rescue for people who can lock the car out first. If the emergency phone is dead, make noise at intervals and save your phone battery for occasional calls or texts.

Preparation that actually helps: carry a small light, a little water and any essential medication with you during the day. During any power problem, use the stairs rather than an elevator. If someone in your household can’t manage stairs, ask the building now how it evacuates people who need help, and check our apartment power outage plan. A keychain or pocket light weighs almost nothing. Our survival flashlight guide explains how to choose by battery type, or you can browse keychain LED flashlights on Amazon.

Hospitals, care homes and medical equipment at home

The commission’s concern about hospitals was their backup power, not instant collapse. Emergency generators serve hospitals, water systems and similar high-priority loads. However, they are “increasingly dependent on electronics to initiate start up,” and their fuel supplies are “generally less than 72 hours” (report page 19). You can’t control a hospital’s backup power.

You can control the plan at home. The commission noted that people who depend on oxygen concentrators, respirators and other powered equipment “will need to find alternative solutions quickly.” Ready.gov’s power outage guidance asks you to:

• Talk to your medical provider about a power-outage plan for each electrically powered medical device.
• Have alternate plans for medicines that need refrigeration. A closed refrigerator keeps food cold for about four hours, and a full freezer holds its temperature for about 48 hours. Ask your pharmacist how long your own medicines can stay unrefrigerated.
• Use any generator outdoors only, at least 20 feet from windows, doors and attached garages, because of carbon monoxide.

Our household power-outage planner turns this into a checklist for your home. The refrigerator battery-backup guide shows how to size a battery for a fridge or other essential loads.

Near a nuclear power plant

The old claim on this page, that reactors run in a “controlled meltdown” and an EMP would therefore cause meltdowns, is wrong on both counts. Reactors run on controlled fission. A meltdown is a loss of cooling, not their normal state. The commission rated nuclear plants as less vulnerable to EMP than other power stations: “The key difference with nuclear power plants is the extensive manual control capability and training.” It notes that every plant has on-site emergency generation. It also notes that regulation forbids a plant to keep operating without reliable outside power for safe shutdown (report pages 31, 48 and 59).

That doesn’t make a long, wide-area blackout trivial for any power plant. But no source we found supports the idea that living near a nuclear plant makes an EMP itself more dangerous. What matters is the plant’s normal emergency plan. The Nuclear Regulatory Commission sets an emergency planning zone of about 10 miles around each plant, where officials plan sheltering, evacuation and potassium iodide where appropriate. A wider zone of about 50 miles is planned for food and water protection. If you live in either zone, know how local officials will alert you. If they ever announce a release, follow their instructions to get inside, stay inside and stay tuned. Our radiation emergency steps explain sheltering and decontamination.

The place you will most likely be: home

For most people the most probable location in any wide-area outage is home. It is the one place where preparation is entirely up to you. The effects the commission worried about most were long ones: lost power, water treatment and fuel distribution. These are the same things a long grid outage takes away. The basics:

• Water: public water depends on electric pumps. Work out what your household needs with our emergency water calculator.
• Information: a battery AM/FM/NOAA weather radio is the most likely way to hear official instructions when the phones and internet are down. Federal EMP guidelines describe battery radios as relatively resilient. See our hand-crank emergency radio guide, or browse battery and crank NOAA weather radios on Amazon.
• Spare electronics: unplugging comes first, and a container comes second. Our guide to protecting electronics from an EMP compares foil, Faraday bags and metal cans against federal guidance and published measurements. It replaces the scrap-metal and filing-cabinet advice this page used to give.
• Staying in touch: agree on a meeting place and an out-of-town contact before you need them, and write them on our printable emergency contact card. Our guide to communications after an EMP explains which radios may help.
• In the car: keep a small kit with water, a light and a phone charger that doesn’t depend on the engine. Browse car emergency roadside kits on Amazon and compare them with our checklist.

For the wider picture of what a large EMP could do, see what an EMP attack is. For a household plan, see our guide to the first three days after an EMP.

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Why this page changed

Earlier versions of this page made claims that the evidence doesn’t support:

• that most cars built since the early 1960s would stop working
• that thousands of airliners would fall from the sky
• that nuclear plants operate in a “controlled meltdown”

Worse, they told readers trapped in an elevator to climb out through the roof hatch, which official guidance says not to do. We replaced that material with the tested findings and official instructions above, and removed product links we could no longer validate.

How we researched this guide

Research method: This is a research-led summary of published evidence and official guidance. It is not personal experience, product testing or engineering certification. Vehicle, traffic-signal, aircraft, hospital and power-plant findings come from the EMP Commission’s Critical National Infrastructures report (April 2008). Page numbers above are the report’s printed page numbers. Elevator instructions come from the NYC Department of Buildings and Otis. Home medical and generator guidance comes from Ready.gov (updated June 4, 2026), and emergency planning zones from the NRC (reviewed August 25, 2026). We checked all of them on November 8, 2026. The commission’s tests used simulators on vehicles built between 1986 and 2003, and nobody can predict exactly how a real event would affect a specific modern vehicle, aircraft or building. We deliberately left out casualty estimates and any judgment of how likely an EMP attack is. Follow local emergency officials if their instructions differ from this page.

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Are You Prepared for a Worst Case Scenario?

The first 72 hours after a disaster are the most critical for survival. Enter your email below to get a checklist of essential items you need in your 72 hour emergency get home bag…

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