Code Green most commonly signals a hospital-wide or partial evacuation in North American hospitals, but that meaning is far from universal. Across different health systems, regions, and countries, the same color code can refer to anything from a combative patient to a bomb threat to a mass-casualty influx. One study of hospitals in a single city found that “Code Green” carried seven distinct meanings depending on which facility you were in. That variability is itself a problem, and understanding what Code Green actually triggers when it does mean evacuation reveals just how complex emptying a hospital really is.
Why Code Green Means Something Different at Every Hospital
Hospital color codes emerged decades ago as a way to alert staff to emergencies without alarming patients and visitors. The idea was simple: broadcast a color over the intercom, and trained employees know what to do. The problem is that no single governing body mandated a universal system for most of the world. A study examining emergency color codes across hospitals in Riyadh found thirty-four different codes in use, with “Code Green” assigned seven separate meanings across different facilities. The most consistently used code was “Code Red” for fire, recognized at about three-quarters of hospitals surveyed, while other colors were a free-for-all.1PubMed Central. Variability of emergency color codes for critical events between hospitals in Riyadh
In practice, Code Green can mean evacuation at one hospital, a missing or elopement patient at the next, and an environmental hazard at a third. Some systems use it for a combative or aggressive individual. A few use it for their mass-casualty response. If you are a patient, visitor, or even a traveling nurse who has just started at a new facility, the color alone tells you almost nothing without site-specific training.
This confusion is measurable. A survey of over 300 hospital employees across five facilities asked them to identify the correct emergencies behind fourteen different codes. On average, staff got the answers right less than half the time. Fire, infant abduction, and cardiac arrest codes were the most recognized, but even those were far from perfect.2PubMed Central. Breaking the Code: Considerations for Effectively Disseminating Mass Notifications in Healthcare Settings Codes that varied most between hospitals, like green and orange, fared worst.
What Actually Happens When an Evacuation Is Called
When a hospital activates an evacuation code, the response follows a structured sequence, though the details vary by institution. Most hospitals use a tiered approach. A partial evacuation clears one floor or wing, typically relocating patients horizontally to another section of the same building. A full evacuation means the entire facility empties, with patients transferred to receiving hospitals across the region.
The hospital’s emergency management team, usually organized under a Hospital Incident Command System, takes control. One person serves as incident commander, coordinating all decisions about which areas evacuate first, where patients go, and how resources are allocated. A systematic review of incident command effectiveness in hospitals identified dozens of variables influencing whether this system actually works under pressure, including the clarity of role assignments, prior drill experience, and communication infrastructure.3PubMed Central. Factors Affecting the Effectiveness of Hospital Incident Command System; Findings from a Systematic Review
Patient prioritization is one of the first decisions. Not every patient faces the same risk from staying, and not every patient is equally difficult to move. Ambulatory patients who can walk are typically evacuated first, since they require the fewest resources. Then come wheelchair-bound patients and those with moderate medical needs. Critically ill patients on ventilators, continuous IV drips, or cardiac monitors go last, not because they matter less, but because moving them safely is a logistical challenge that requires specialized teams and equipment. A consensus statement from a major critical care society laid out detailed recommendations for ICU evacuation, including patient transport preparation, equipment checklists, and regional distribution planning for receiving facilities.4PubMed Central. Evacuation of the ICU: care of the critically ill and injured during pandemics and disasters: CHEST consensus statement
Why Hospital Evacuations Are So Much Harder Than Building Evacuations
Emptying an office building in a fire drill is straightforward. People stand up, walk to the stairwell, and leave. Hospitals are fundamentally different. A large portion of the building’s occupants are the reason the building exists: they are sick, injured, sedated, post-surgical, or physically unable to move on their own. Many are connected to machines that are themselves keeping them alive. You cannot simply unplug a ventilator and carry a patient down five flights of stairs without a detailed plan for how they will breathe during the trip.
Vertical evacuation, moving patients down stairwells, is the bottleneck that defines hospital evacuation speed. Elevators are usually off-limits during fires and often unreliable in other emergencies like earthquakes or floods. Researchers have modeled how quickly patient beds can be moved horizontally through corridors, accounting for corner-turning and speed reductions over multiple trips, to predict total evacuation times and the probability of completing an evacuation safely within a given window.5Elsevier. Estimating horizontal movement performance of patient beds and the impact on emergency evacuation time But horizontal movement is the easy part. Going down stairs with a bedridden patient is where evacuations slow to a crawl.
Moving Patients Down Stairs
Specialized evacuation devices exist for exactly this problem, but none of them are fast. Simulations of hospital evacuations using various movement devices found that vertical travel speeds with assisted devices averaged between about 0.6 and 0.84 meters per second, far slower than a healthy adult walking down stairs.6Fire Technology. Simulating Movement Devices Used in Hospital Evacuation That speed might not sound slow in the abstract, but when multiplied across dozens or hundreds of patients, each requiring their own trip down a stairwell, the total evacuation time stretches dramatically.
Sled-type stair descent devices are among the most commonly studied. In one evaluation, twelve firefighters used six different sled-type devices to evacuate simulated patients down staircases of two different widths. All descent speeds were below those seen in normal pedestrian stair evacuation. Devices operated by two people generally moved faster than those run by a single operator, and high-friction materials under the sleds helped with control on the stairs themselves but made landings harder. Shorter devices had fewer collisions with walls on stairwell landings, which is a real concern in the narrow stairwells many older hospitals have.7PubMed. Evaluating the physical demands when using sled-type stair descent devices to evacuate mobility-limited occupants from high-rise buildings
A qualitative study of clinicians in Iran highlighted that many imported evacuation devices are incompatible with local hospital infrastructure, emphasizing the need for lightweight, heat-resistant, manually powered equipment that requires as few staff members as possible to operate.8Research Square. Hidden Barriers and Operational Gaps in Emergency Evacuation Equipment Design Requirements for Bed-dependent Patients: A Qualitative Study in Iran That finding applies broadly: hospitals in older buildings, developing countries, or rural areas with narrow corridors and limited staff face even steeper challenges than large urban medical centers.
Evacuating the Most Vulnerable Patients
Neonatal intensive care units present some of the most extreme evacuation challenges in medicine. NICU patients are tiny, physiologically unstable, often on ventilators, and unable to communicate distress. Their equipment is specialized and not easily portable. Published data on NICU evacuations in real disasters is thin, which is itself part of the problem: hospitals have relatively little evidence base to draw on when planning for these scenarios.
One of the most thoroughly documented cases came from Hurricane Sandy in 2012. When a power outage hit New York University Langone Medical Center due to a coastal surge, staff evacuated twenty-one neonates from the NICU to receiving hospitals across New York City in four and a half hours. Data from the evacuation and staff debriefings identified several critical success factors: a clear command structure, backup systems for personnel, communication, medical records, and equipment, as well as regional coordination with receiving hospitals and special attention to families.9Pediatrics. Evacuation of a Neonatal Intensive Care Unit in a Disaster: Lessons From Hurricane Sandy Staff carried babies down darkened stairwells using flashlights, hand-ventilating the sickest infants with bag-valve masks because the ventilators had no power.
A similar scenario played out during the 2016 Kumamoto earthquakes in Japan, where a tertiary neonatal center had to evacuate its patients. Infants with congenital heart disease, those on invasive or non-invasive respiratory support, and those with higher clinical risk scores were more likely to require transfer to facilities outside the affected prefecture, and their evacuations took significantly longer to execute.10Neonatology. Evacuation of a Tertiary Neonatal Centre: Lessons from the 2016 Kumamoto Earthquakes The sicker the baby, the harder and slower the move.
Communication Is the Weakest Link
When ICU providers who participated in Hurricane Sandy evacuations were surveyed afterward, forty-three percent identified communication as the single biggest barrier to an effective evacuation. The equipment they found most helpful included flashlights, transport sleds, and oxygen tanks with respiratory therapy supplies.11PubMed Central. Evacuation of Intensive Care Units During Disaster: Learning From the Hurricane Sandy Experience Notably, most of these providers had little prior knowledge of evacuation protocols and no experience with vertical evacuation before Sandy forced them into it.
The communication problem runs deeper than just knowing what code to call. During an active evacuation, teams need real-time information about which patients have been moved, which stairwells are passable, how many beds are available at receiving hospitals, and whether ambulances are en route or stuck in traffic. In a power failure, intercom systems and electronic medical records go dark. Cell networks often overload during regional disasters. Hospitals that had invested in backup communication systems, like two-way radios and printed patient tracking sheets, fared better than those relying on a single infrastructure.
This connects back to the broader color-code confusion. If a hospital broadcasts “Code Green” and a significant fraction of staff are unsure whether it means evacuation, active shooter, or something else, the first minutes of the response are wasted on clarification rather than action. Staff who correctly identified emergency codes in surveys were more likely to have received training at orientation, to know how to activate codes, and to have worked at the facility longer.2PubMed Central. Breaking the Code: Considerations for Effectively Disseminating Mass Notifications in Healthcare Settings Newer employees and those who moved between facilities, an increasingly common pattern in healthcare, were at higher risk of misidentifying codes.
The Push to Replace Color Codes with Plain Language
The confusion around color codes has fueled a growing movement to scrap them entirely in favor of plain-language alerts. Instead of “Code Green,” the overhead announcement would say something like “Attention: Evacuate Building A to the parking structure immediately.” Everyone, whether a veteran nurse or a visiting family member, understands what that means without any training.
Advocates for this approach argue that relying on color codes, even standardized ones, interferes with integrating hospital responses into the broader National Incident Management System used by fire departments, police, and emergency management agencies. Those agencies do not use color codes; they use plain English. When a hospital incident commander needs to coordinate with city fire services during a real evacuation, translating between internal color codes and external plain-language communication adds an unnecessary layer of friction.12PubMed. Hospitals should replace emergency codes with plain language
Research on this question found that an overwhelming majority of healthcare professionals preferred voluntary plain-language emergency code standardization over the current patchwork of individual code systems.13PubMed. Plain language emergency alert codes: The importance of direct impact statements in hospital emergency alerts Despite that preference, adoption has been slow. Color codes are deeply embedded in hospital culture, training materials, and signage. Changing them requires retraining thousands of employees, updating infrastructure, and overcoming institutional inertia.
Some jurisdictions have mandated standardization. Ontario, Canada, adopted a province-wide color code system to reduce inter-hospital confusion. A handful of U.S. states have pushed for similar efforts. But even standardized color codes do not solve the fundamental problem: a visitor hearing “Code Green” over the intercom still has no idea what to do, while “Please evacuate to the nearest exit” is self-explanatory.
What Evacuations Cost Hospitals
Beyond the immediate safety concerns, hospital evacuations carry enormous financial consequences. Facilities lose revenue from cancelled surgeries, delayed admissions, and diverted emergency patients for every hour the evacuation is in effect. If the building sustains physical damage, the costs multiply. A case study of a coastal Georgia hospital examined the economic impact of hurricane evacuations, and for context, Hurricane Katrina alone caused more than forty-three million dollars in damages to community health centers in New Orleans.14PubMed Central. The Economic Impact of Hurricane Evacuations on a Coastal Georgia Hospital: A Case Study
These costs create a tension in decision-making. Evacuating too early means losing revenue and displacing patients who may not have been at risk. Evacuating too late puts lives in danger. Hospital administrators sometimes delay evacuation calls because they are weighing financial consequences against uncertain forecasts, and that delay can have serious safety implications.
The Toll on Staff
Hospital evacuations are traumatic for the people carrying them out. Staff members in evacuations work long shifts under chaotic conditions, often making life-or-death transport decisions for patients they may have only recently met. When an evacuation stretches into a prolonged displacement, where the hospital cannot reopen for weeks or months, the psychological burden deepens. Research on a complete hospital evacuation found that as staff began to realize the displacement would be extensive, frustration, complaints, and a sense of disenfranchisement emerged.15Journal of Healthcare Management. Supporting Staff Through a Complete Hospital Evacuation and Extended Displacement Period
Staff who participated in the Hurricane Sandy evacuations described carrying patients down pitch-black stairwells, manually ventilating critically ill patients for extended periods, and losing contact with the incident command team for stretches of time. The physical and emotional exhaustion from these events lasts well beyond the emergency itself, and many healthcare workers report feeling underprepared despite having attended some form of disaster training. The gap between a tabletop drill in a conference room and an actual evacuation in a darkened, flooded building turns out to be vast.
How Simulation and Modeling Are Trying to Close the Gap
Researchers have been developing computer models to simulate hospital evacuations, hoping to identify bottlenecks and test strategies before a real emergency forces the issue. A review of hospital evacuation simulation models found that some existing platforms, like Building-Exodus and Pathfinder, are capable of simulating hospital-specific conditions reasonably well. However, most current agent-based evacuation simulations rely on rule-based artificial intelligence rather than self-learning systems, meaning the simulated “patients” and “staff” follow pre-programmed behaviors rather than adapting dynamically to changing conditions the way real people do.16Elsevier. A review on the hospital evacuation simulation models
The potential of more adaptive models is significant. A simulation that could learn from thousands of virtual evacuation scenarios might identify non-obvious strategies, like the optimal order in which to clear specific wards, or the point at which adding more staff to a stairwell actually slows things down due to crowding. For now, most hospitals still rely on periodic physical drills supplemented by relatively simple evacuation-time calculations. The gap between what simulation technology could offer and what hospitals actually use in their planning remains wide.