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Risks7 min readAndi Arapi

The ways an AED stops being useful

A defibrillator almost always fails before it’s switched on. Not through a fault: because it can’t be found, can’t be reached, or nobody knows it’s there.

The fault isn’t the main risk

In most people’s minds, the risk with a defibrillator is that it won’t start. In practice that case is rare: AEDs run a periodic self-test and report by themselves when something is wrong. The ways a device becomes useless are more mundane, and all of them sit outside the box.

The first is accessibility. An AED inside an office that closes at 6pm is an AED that doesn’t exist for two thirds of the day, and cardiac arrest doesn’t check opening hours. The second is signage: without a sign visible from the point where someone is giving help, the nearest device is the one you know about, not the one that’s there. The third is awareness: do the people who work in that building know it exists? Do they know where the key is, if the cabinet is locked?

Data

When a mapped AED can be reached

The 170,253 defibrillators in our dataset, split by what they state about their own hours. Tap a segment for the detail.

Hours unknown71,635 devices don’t state when they can be reached. Anyone looking has to go and see: it’s the piece of information missing most often, and the most expensive one to be without.

Always open66,966 devices stated as accessible 24 hours a day. They’re the only group you can count on at any hour — and that’s fewer than four in ten.

Limited hours31,652 devices can only be used at certain times. That isn’t a flaw in itself: it becomes a risk when nobody knows before running there.

Out of 170,253 devices mapped worldwide.

Source: OpenStreetMap, our analysis of the SOS DAE dataset

What the public data doesn’t say

People who manage a defibrillator often assume that, since it’s registered somewhere, it can also be found. Open data says otherwise.

We counted, one by one, the gaps in the worldwide dataset the app uses. These aren’t estimates: they’re the empty fields.

Data

What’s missing from public AED data

How many devices, out of 170,253, lack each piece of information.

  • No address153,334

    Nine out of ten. The coordinates remain: they take you to the building, not to the cabinet.

  • No verification date147,046

    Nobody knows whether they’re still there. A point on a map with no date is a piece of information whose age is unknown.

  • No name140,499

    “Defibrillator” and nothing else: once you arrive, you don’t know which door to open.

  • No name, address or directions37,851

    A point and nothing more. These are the cases where the map says an AED exists but doesn’t help you find it.

Hover over a bar — or tab to it — for the detail.

Source: OpenStreetMap, our analysis (dataset of 23 July 2026)

What the owner can do

The good news is that all three gaps close without buying anything. They’re hours of work, not budget.

  • Put the sign where it’s needed: not next to the AED, but at the point from which someone will have to look for it.
  • State the real access hours, even if they’re inconvenient. “Mon-Fri 8-18” is useful information; silence isn’t.
  • Write down where it actually is: “ground floor, corridor by the first-aid room, next to the fire extinguisher”.
  • Let the people who work there know it exists, where it is, and that no training is needed to use it.
  • Update the point on the public map: that’s what someone who doesn’t know the building will see.
  • Record the date of the last check: it’s the field missing from 147,046 devices out of 170,253.

The minute that counts

The ERC guidelines say that every minute without defibrillation takes away roughly ten percentage points of the chance of survival. That’s why none of the above is bureaucracy: a missing sign costs minutes, and minutes are the only currency in this business.

None of the risks listed here has anything to do with the quality of the device. They’re all about the organisation around it — which is exactly the part that can be fixed.

Takeaways

  • An AED almost always fails before it’s switched on: locked door, no sign, nobody who knows it’s there.
  • Fewer than four mapped devices in ten state that they’re accessible 24 hours a day.
  • 147,046 defibrillators out of 170,253 have no verification date: nobody knows whether they’re still in place.

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