UK Quarterly Project/2024/2024 Q2 Project: Defibrillators

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OSM magnifying glass with the ISO 7010 E010 AED icon in focus of the glass.


The second UK Quarterly Project of 2024 (April, May, June) is on Defibrillators. The aim is to improve the quantity and quality of OSM data on AEDs in the UK.

There is a central registration service for AEDs called The Circuit that ensures ambulance services have the details in case of an emergency. Robert Whittaker has a tool that compares the OSM data with that in The Circuit. We could also use this to try to help improve the data in The Circuit.

Suggested Tasks

  • Survey and map AEDs that aren't already on OSM
  • Improve the metadata and positional accuracy of existing AEDs
  • Add The Circuit reference numbers of AEDs to OSM
  • Try to contact guardians of AEDs that are missing or incorrectly located in The Circuit (the database used by ambulance services) to encourage them to register them / fix the location.

Surveying and Mapping new AEDs in OSM

AEDs are mapped in OSM with a node tagged with emergency=defibrillator.

AEDs are not displayed on the default OSM map style. But you can view them on some third-party maps:

You may have local knowledge of missing AEDs. The Defib Comparison Tool can also be used to find locations to survey. Blue circles are used to highlights AEDs in The Circuit and the NDDB that aren't currently mapped in OSM. (Note that we do not have permission to use the data from The Circuit or the NDDB directly in OSM.)

In most cases, a ground survey is going to be needed to map a new AED in OSM. It can be useful to take a photograph in the field, to ensure you can map the AED in the correct position relative to surrounding buildings etc. Particularly in urban areas, you may find reasonably up-to-date street-level imagery can be used to map AEDs, if you know a location to check. Mapillary, KartaView, and Bing Streetside are available in iD and other editors.

On an Android device the StreetComplete "Things" layer can be used to view and add new defibrillators on the go, this will usually trigger follow-up questions to refine some secondary tags.

Improving the metadata and positional accuracy of existing AEDs in OSM

Useful tags to add include:

  • defibrillator:location=* — A human-readable description of where the AED can be found.
  • ref=* — Sometimes there is a reference number displayed on the case.
  • access=* — Use 'yes' if it's in a public place, 'permissive' if it's on private land, but it appears to be intended for general public use, and you can get to it without difficulty, and 'private' otherwise.
  • indoor=* — use 'yes' if within a building, and 'no' otherwise. (AEDs in bus shelters and former telephone boxes, are probably best tagged as indoor=no.)
  • opening_hours=* — Use to specify the precise times an AED is available (e.g. if it's within a shop). '24/7' can be used for AEDs that are available all the time.

Also check the AED node is in the correct location, and surrounding features (e.g. buildings, roads, paths, etc) are mapped and correctly aligned. Aerial imagery aligned with the Land Registry Cadestral Parcels (available as a layer in most editors) is useful for this.

Adding Circuit Refs to AEDs

Each AED listed in The Circuit has a 32-character unique reference number in the form of a UUID: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX. Robert Whittaker obtained permission from the British Heart Foundation to add these numbers to OSM. Please use the ref:GB:the_circuit=* tag for this. Doing so confirms the matches in the Comparison Tool, and makes the comparison more reliable than just using proximity between the datasets. A semi-colon separated list of UUIDs can be added to not:ref:GB:the_circuit=* to prevent incorrect matches in the tool.

Contacting AED Guardians to report Errors / Omissions in The Circuit

While not directly benefiting OSM, there is a clear public benefit in having The Circuit being as complete and accurate as possible. Those working on this QP are therefore encouraged to help achieve this. Information about the AEDs in The Circuit is provided by the owner/operator of each AED, referred to as the Guardian. It is this Guardian that needs to be contacted about registering and AED or fixing any incorrect information.

  • If you find an AED that is not listed in The Circuit or the NDDB, it would be useful to try to contact the Guardian and encourage them to register it. Unmatched AEDs in OSM are flagged with red circles in the Defib Comparison Tool. But The Circuit data there is only updated once a month, so do also check the live data in DefibFinder as well. To avoid basing actions on out of date or inaccurate OSM data, it would sensible to try to contact people about an AED you have personally verified within the last few days.
  • If you find an AED that is listed in The Circuit with an incorrect location (out by say 200m or more), it would be useful to try to contact the Guardian to encourage them to correct the location. As above, do also check the live data in DefibFinder first, and only do this if you have up-to-date personal knowledge of the true location.
  • Some AEDs appear to have been registered more than once with The Circuit. This is more difficult for individual guardians to understand and fix. In the Defib Tool there is a manually maintained list of potential duplicates. Mappers can request additional pairs be added, and it's also possible to ask for access to be able to add/edit them yourself.

To contact the Guardian in the above cases, you will first need to work out who the Guardian of the AED is. Often this will be the owner of the building the AED is attached to. For those in old phone boxes in villages, it will often be the Parish Council. Some suggested texts of emails to send can be found at [1]. Even if you don't get in touch with the right person, they may well know who the actual Guardian is.

Useful wiki pages

Data Sources

The Circuit

The Circuit is run by the British Heard Foundation (BHF) on behalf of the UK's ambulance services. The data in The circuit is provided to the ambulance services so they can direct 999 callers to an appropriate location in an emergency. The system provides close to real-time information on AED availability. Most of the AEDs listed in The Circuit are shown on BHF's Defib Finder map, and the full dataset can be downloaded from [2]. (A small number of Defib owners chose to hide their AEDs from this data, but this is discouraged by BHF.)

BHF maintain the system and the database, but the main responsibility for managing the data rests with the Ambulance Services. They in turn relay on the the individual operators -- referred to as "guardians" -- of each AED to register them in The Circuit and keep their data up to date. This means that if we notice any errors or omissions in The Circuit, the best place to report these to is the Guardian of the AED in question. Information about the Guardians is not published, but it is often fairly easy to guess a business/organisation from where the AED is located.

Data in The Circuit is not licensed for use in OSM, but Robert Whittaker has obtained permission for us to add the UUID reference numbers to OSM objects to facilitate matching between the datasets.

National Defibrillator Database (NDDB)

The National Defibrillator Database is run by the Community Heartbeat Trust charity. It is believed that recipients of AEDs they help fund need to register them in the NDDB. The NDDB pre-dates The Circuit. At least before The Circuit was up and running, the data from the NDDB was passed to Ambulance Services for emergency use. It's not clear if this is still happening. It may be that ambulance services are using legacy lists alongside the live data from The Circuit.

There was initially some conflict between BHF and CHT over the two databases, with CHT telling guardians of their AEDs not to register them with The Circuit as well as the NDDB. It's not clear what the current status is, and whether there is a plan to migrate AED listings from the NDDB to The Circuit in bulk. So for now, it would be best to avoid contacting the guardians of NDDB-registered AEDs that are missing from The Circuit.

There is no licence to use the data from the NDDB in OSM.