No_intervention: Control sites

* For all 1-1-2 calls with suspected cardiac arrest to the emergency dispatch center will activate a two-tiered response consisting of dispatch of an ambulance with an emergency medical technician, a physician-staffed mobile emergency care unit, and citizen first responders through the Heart Runner app.~* The medical dispatcher offers telephone assisted cardiopulmonary resuscitation (CPR) to bystanders. Furthermore, if more than two bystanders are present and an AED is accessible within 1½ minute travel distance (depending on the type of terrain), then one bystander is guided to localize and retrieve the AED.

Experimental: Intervention sites

As a supplement to the standard care as described in the control arm, the following will be supplied:~* Strategical deployment of AEDs with 24:7 availability and 1½ minute walking distance to every residence within the area. The AEDs will be registered with the AED network and thus linked to the emergency dispatch center.~* The emergency dispatch center will retrieve data from used AEDs.~* For each interventional area, approximately 120 residents will receive a course in CPR and AED use and subsequently be recruited as citizen responders so that they can be activated through the HeartRunner app in case of a nearby cardiac arrest.