Defibrillators keep office hours.
After Hours maps New York City's 4,032 public defibrillator locations by the hour, showing which ones sit behind an unlocked door, and where a 24/7 cabinet would reach the most cardiac arrests.
On a school-year Tuesday at 2 PM
2,636 of 4,032 locations open, by published or school hours
The outer ring is AEDs you can reach. The inner ring is when 2025's cardiac-arrest calls came.
Drag the hand, or use the arrow keys.
Half of them are in schools.
1,925 of the city's 4,032 registered AED locations are school buildings. Outside Manhattan it is 69%: Brooklyn 71%, the Bronx 72%, Queens 67%, Staten Island 58%. In Manhattan, where offices and gyms carry the load, it is 21%.
That is one school-year week: 168 hours, 55 of them reachable. From late June to early September, all 168 hours are locked. On a Tuesday afternoon in August, 711 locations are open by their published hours across the whole city.
It worked because the door was open.
On a Monday afternoon in early 2025, a preschool teacher collapsed during an after-school staff meeting at Yorkville Community School, P.S. 151, on the Upper East Side. A colleague ran down a flight of stairs for the school's AED. Five teachers gave CPR and three shocks before the FDNY arrived, and she survived.
“If someone in cardiac arrest goes four minutes without intervention, the brain begins to deteriorate.”
Ask the map about the sidewalk outside the same school:
- Monday, 4 PMThe school's own AED, open.
- Monday, 7 PMLocked. The nearest open one is a gym, a 12-minute walk.
- July, Monday 4 PMLocked. The nearest open one is an 11-minute walk.
Cardiac arrest keeps no hours.
In 2025, the FDNY sent ambulances to 25,448 calls that its dispatchers closed as cardiac arrest. 16,285 of them, 64%, came while school buildings were shut.
AED locations open by published or school hours: 2,298 at 5 PM on a school Tuesday, 250 at 6 PM, 52 at 3 AM on Sunday.
Cardiac-arrest calls, 2025, by hour of day
AED locations open by published or school hours, school-year Tuesday
Covered on paper, locked at night.
Every AED map counts every defibrillator as available. We weighted each street by where and when 2025's cardiac arrests actually happened, then asked whether the nearest AED within a two-minute walk was open at that hour. 69% of the coverage a time-blind map shows was behind a locked door.
What a time-blind map shows
What was open when the calls came
Share of call-weighted street area within a two-minute walk of an AED, routed on real streets by Amazon Location Service.
This holds up under the kindest assumption: even if every venue whose hours are unknown were open around the clock, 39% of the coverage would still be locked away. Keep schools open until 9 PM and it is 35%.
The ten schools to change first
The ten school defibrillators that would have put the most of 2025's after-hours cardiac arrests within a two-minute walk, if each sat in a 24/7 cabinet on the school's street wall. Top of the list: P.S. 053 Basheer Quisim in ZIP 10456.
A printable brief for each of the 100
The fix is a box on the wall.
A weatherproof cabinet on the outside of a building keeps a defibrillator reachable at 3 AM, on Sundays and through August. The device is the same one already inside the school. Only the door changes.
For 69 of the 100 schools on our list, Overture Maps shows a fire station, police station or hospital within 400 m that is staffed through the night: a second place a cabinet could go.
What you can do here
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Scrub the week
Drag through any hour of a school-year week or a summer week and watch each two-minute walking area go dark.
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Collapse here
Drop a pin anywhere. Amazon Location Service walks the real streets to the nearest AEDs and tells you which one is open, and how much longer it takes to reach.
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Bring your own list
Upload a CSV or GeoJSON of places with opening hours: AEDs in your city, naloxone boxes, cooling centres. Addresses are turned into map points for you.
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Get an API key
Create a key in one click and call the same engine from your own code, or from Claude and other AI assistants through MCP.
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Print a school brief
One page per ranked school, ready to take to a principal or a council office: an Amazon Location street map of its walking area, its week, the nearest 24/7 building and the evidence.
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Hear both sides
Two AI agents argue whether a school's AED should move outdoors, citing only the data. A third gives the verdict and the next step.
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Take the data
Every table behind the map, as CSV, under the same open licences as the sources.
Plain answers
What is an AED?
An automated external defibrillator is a portable box that checks the heart's rhythm and, if it finds one that a shock can fix, delivers that shock. It speaks each step out loud. You do not need training to use one, and it will not shock someone who does not need it.
Why does the time of day matter?
Because a defibrillator inside a locked building cannot be fetched, and the shock has to come before the ambulance does. In a large US study of witnessed public cardiac arrests with a shockable heart rhythm, 66.5% of people shocked by a bystander with a public AED survived to leave hospital, against 43.0% of those who waited for the ambulance crew (Pollack et al., Circulation, 2018).
Is this an emergency service?
No. It is a planning tool for cities, schools and residents. In an emergency, call 911 first: dispatchers can talk you through CPR and send help.
Where do the opening hours come from?
New York's AED registry has no hours, so we built them, and every location says where its hours came from. 1,925 schools use the public-school calendar. 742 venues use the opening hours Amazon Location Service publishes for them. For 1,278 more, Amazon Bedrock made an estimate that we show but never count as open in the headline numbers. 87 remain unknown.
How good are the AI estimates?
We tested them blind on 742 venues whose real hours we know. They matched the published hours for 85% of the hours in a week. Headline numbers use published hours and the school calendar; you can switch the AI estimates on in the map.
How is "covered" measured?
Amazon Location Service routed a two-minute walk from each of the 4,032 locations along real streets. We laid a 50-metre grid over the city, counted which grid squares fall inside an open AED's walking area at each hour of the week, and weighted each ZIP code by the cardiac-arrest calls that came from it at that hour.
Can I check my own city?
Yes. Upload a list of places with opening hours on the Your data page, or call the API. France already makes every AED owner declare hours: in Paris, AEDs open by their declared hours fall from 838 on a Tuesday afternoon to 219 at 3 AM on Sunday.
Photographs from Wikimedia Commons: P.S. 108, Brooklyn, by Smallbones (CC BY-SA 3.0); P.S. 91, Highbridge, by Jim.henderson (public domain); Public School 45, Brooklyn, by Clyde Charles Brown (CC BY-SA 4.0); Dingle cabinet by Mucklagh (CC BY-SA 4.0); Mundesley cabinets by Kolforn (CC BY-SA 4.0); Bielsko-Biała AED by Silar (CC BY-SA 4.0). Full credits and links.