The number of Automated External Defibrillators (AEDs) a building needs is not determined by a simple formula based on square footage. Since survival rates decrease dramatically with every minute of delay, the placement strategy must focus entirely on response time, not on a fixed ratio. The goal is to establish a framework that ensures the device can be retrieved and used fast enough to make a difference.
The Core Metric: Achieving a 3-Minute Response Time
Time is the single most important factor in surviving sudden cardiac arrest. For every minute that passes without defibrillation, the victim’s chance of survival decreases by approximately 7% to 10%. Since emergency medical services often exceed seven minutes, immediate bystander intervention with an AED is often the only chance for survival.
Leading health organizations, including the American Heart Association (AHA), recommend that an AED be accessible for use within three to five minutes of a collapse. This short window is what drives all AED placement decisions within a facility. The total response time is a sequence of four distinct events: recognizing the collapse, sending a person to retrieve the AED, the actual retrieval time, and the time taken to deploy the device and deliver the first shock.
An AED placement program should aim for a maximum 90-second one-way walking time to any device from any location in the building. This 90-second retrieval time, combined with the 90-second return time, accounts for a three-minute round trip, leaving a small buffer for deployment. If a person in the farthest point of a building cannot reach an AED and return to the victim within this time frame, an additional AED is needed to cover that zone. The physical walking time is the most controllable variable in the entire chain of survival.
Facility Assessment: Determining Placement Density
To achieve the stringent three-minute goal, a detailed facility assessment must be performed, focusing on internal obstacles and population flow rather than simple floor plans. The assessment should begin by selecting a potential AED location and then physically walking to the farthest point it is expected to cover, timing the round trip at a brisk pace. If this timed walk exceeds three minutes, an additional AED is necessary to shrink the coverage area.
The physical layout presents the most significant barriers to a rapid response. Stairwells, elevators, and locked doors—especially those requiring special access—can critically delay the process and must be factored into the walking time. In multi-story buildings, it is often necessary to place at least one AED on every floor if using an elevator or stairs would cause the response time to exceed the three-minute limit.
Beyond purely physical barriers, population density requires priority placement regardless of square footage. High-occupancy zones, such as cafeterias, large conference rooms, and main lobbies, should have a device nearby due to the sheer number of people present. High-risk zones, including on-site fitness centers, manufacturing floors, or loading docks, also warrant dedicated placement due to physical exertion or electrical hazards. Placing the device in a highly visible, well-signed, and unlocked location is paramount to ensuring accessibility.
Regulatory Landscape and Professional Recommendations
Currently, no overarching federal law mandates the placement of AEDs in all private or commercial buildings. While the Occupational Safety and Health Administration (OSHA) encourages AED implementation, it does not enforce a specific requirement. However, many states and local jurisdictions have enacted specific legislation requiring AEDs in certain high-traffic or high-risk locations, such as schools, large sports venues, and airports.
Organizations like the American Heart Association and American Red Cross strongly advocate for widespread AED programs based on the three-minute access standard, irrespective of legal mandates. These professional recommendations serve as the recognized standard of care for building safety programs. Furthermore, the use of an AED by an untrained bystander is protected in all fifty states through Good Samaritan laws, which provide legal protection to individuals attempting life-saving assistance.