About 16% of the global population live with a disability, and this proportion is projected to increase as we live longer [1]. These disabilities are the result of a range of impairments, including those that limit cognitive, physical, sensory functions as well as mental health. Many individuals also experience limited function transiently with pregnancy, injury or illness [2]. Impairments and other needs that affect participation in the fundamental physical and cognitive activities needed for daily life are generally termed functional limitations [3]. For instance, while an impairment may be the loss of a limb (deficiency in body structure), the associated functional limitation may be the inability to walk (activity limitation).

There has been a growing movement around the world to ensure that the built environment is accessible to meet the needs of people with functional limitations. The Americans with Disability Act was passed in 1990, and the United Nations passed the Convention on the Rights of Persons with Disabilities in 2006 ^[4][5][4,5]. Canada has committed to the goal set out by the United Nations to provide universal access (accessibility) to public spaces by 2030 and also passed the Accessible Canada Act in 2019 ^[6][7][8][6,7,8]. However, a critical aspect of accessibility is “egressibility”, which attempts to ensure that all occupants can be evacuated safely in the case of an emergency [6]. For instance, a review by the National Research Council of Canada found that evacuation strategies for occupants with functional limitations have been given little attention to-date [9]. Similarly, the Canadian Commission on Building and Fire Codes highlighted the need to revise strategies for evacuating people with disabilities from the built environment as a key target of future work [6].

The need for improved egressibility is more important now than ever. There is evidence from over the last 20 years from countries like Canada that (i) the proportion of people with living in the community with an impairment has increased; and (ii) the severity of these impairments has also increased ^[2][9][2,9]. In addition, assistive technologies that are designed to support the evacuation of individuals with functional limitations have advanced over the past decade ^[10][11][10,11]. Finally, it is important to note that existing guidelines for emergency evacuations tend to focus only on fire-related events. However, that has been a growing need for evacuations because of flooding, power outages or other extreme weather events due to climate change ^[12][13][12,13]. Evacuating people in these types of weather-related events may benefit from different approaches.

First, the results highlight the vulnerability of older adults in fire emergencies, given that they often require additional time to escape buildings and are overrepresented in fire emergency fatalities ^[14][121]. In fact, according to Diekman et al. (2010) ^[15][120], older adults are 3.7 times more likely to die in house fires than the rest of the population. These statistics are especially worrying given that the proportion of community-dwelling older adults is rising, many of whom live alone. Increasing available egress time during a fire emergency through effective notification solutions would have aided 25% of fire victims who were fatally or non-fatally injured in the US ^[16][123].

Second, the results show insufficient research on effective notification solutions for those with severe (60–80 dB) or profound (80+ dB) hearing loss. In the United States, 6.6 million people aged 12+ have severe to profound hearing loss in at least one ear, with three-quarters of the group being older than 60 years old ^[17][124]. Ito et al. (2013) ^[18][34] proposed an information delivery system for people with profound hearing loss that displays disaster information on LED displays installed in residential and public buildings, though some components of this technology are now outdated. There was also one study that adapted notification solutions based on a person’s impairment, technological device, and emergency, though the solution would require a user to have a mobile phone or other device on hand at all times and may not be suitable for imminent emergencies that require immediate evacuation ^[19][28]. 

Another theme that emerged among the results is the need to often tailor notification solutions to the building type. This was demonstrated by Schulz et al. (2008) ^[20][31], who designed and evaluated an aspirated recessed point-type smoke detector for mental health hospitals that complies with both building standards and clinical patient safety requirements.

2.2. Wayfinding Solutions

The results demonstrate that, in contrast to outdoor wayfinding, accessible indoor wayfinding systems for individuals with functional limitations continue to be an emerging area of research. This is in part due to the increased challenges with (1) selecting location technologies that can effectively be used indoors, and (2) accommodating the common needs and behaviours of individuals with functional limitations when evacuating from an indoor environment, such as minimizing turns, navigating obstacles, and remaining close to walls for spatial orientation. First, in contrast with outdoor wayfinding, global navigation satellite systems (GNSS) such as GPS cannot be used in an indoor environment with accuracy due to interference from the structural materials of buildings. The second challenge of indoor wayfinding systems is accounting for the increased obstacles and turns present in indoor environments and subsequently tailoring wayfinding solutions to the unique needs and behaviours of individuals with functional limitations as they evacuate from such environments. For instance, individuals with mobility impairments often require routes that traverse wide hallways with the least number of obstacles and turns ^[21][37]. Individuals with vision impairments often walk close to walls and handrails for spatial orientation, especially in unfamiliar environments ^[22][47]. As such, the most common features of wayfinding apps were obstacle avoidance, turn minimization, route recalculation, congestion management, and route personalization according to disability. Accessible indoor wayfinding algorithms, apps, and other devices are of great importance, as many individuals with functional limitations tend to exit the way they entered due to fear that other routes may not be accessible (Lena et al., 2012) ^[23][30]. This could be concerning if the route chosen is unsafe in the event of an emergency. It is also worth noting that wayfinding technologies should not impede how people with functional limitations organically interact with their support devices or built environment. For instance, it has been suggested that integrating electronics in a white cane may impact the sensitivity of those with vision impairments due to a change in the weight of the cane ^[22][47].  While most articles focused on those with sensory or mobility limitations, one study considered individuals with cognitive impairments ^[24][42]. Given the heterogeneity of this population, further research was encouraged to validate wayfinding solutions that promote their autonomy and address their unique challenges, such as information processing, problem-solving, and attention in the face of stressful situations. It should be noted that Bukvic et al. (2021) ^[25][14] identified a lack of studies that connect the impact of cognitive impairments on evacuation performance in their scoping review, and may be a necessary step before identifying suitable evacuation solutions for the population. In terms of building types, there was good representation among the wayfinding solutions with some articles focusing on unique building types such as historical buildings and public transport terminals ^[23][26][27][30,39,44]. Subway egress is especially unique given that evacuees usually need to climb stairs to reach the ground level and that subway stations are often crowded and vulnerable to bottlenecks, even without emergencies ^[26][39]. The results also show a need to make historical buildings more accessible ^[23][30]. On that front, wayfinding tiles and arrows made of photoluminescent materials may be a robust and cost-effective way of retrofitting historical buildings with a wayfinding aid that preserves important structural elements of the building ^[23][27][30,44]. 

2.3. Egress Solutions

2.3. Egress Solutions

Results demonstrate that there has been significant attention in the literature on horizontal and vertical evacuation solutions for high-rise buildings and hospitals. Nearly all of the egress articles that focused on high-rise buildings tested their evacuation devices in a simulated or real-world environment. In contrast, only three of the seven hospital-focused articles tested their egress solutions ^[28][29][30][63,64,67]. Devices most suitable for vertical evacuation often differed from those most suitable for horizontal evacuation due to the inherent differences in the evacuation paths, the unique challenges of stairwells, and differences in the number of rescuers needed based on each type of evacuation ^[31][54]. Whereas horizontal evacuation refers to egress to a place of safety or an adjacent fire compartment on the same floor of a building, vertical evacuation involves descending or ascending to an exit and often requires the use of stairs.

An important challenge to the use of stair descent devices is the need to increase movement and efficiency through the landing areas of stairwells, given that this is where stair descent devices were the slowest throughout the evacuation route ^[29][32][57,64]. Slow-moving stair descent devices may increase congestion in landing areas, which are already vulnerable to bottlenecks ^[33][127]. 

An inconsistency observed among the study methodologies was whether the rescuers recruited in the simulation trials were trained in the operation of rescue devices. This led to discrepancies in average egress times across different articles ^[32][34][56,57]. Lavender et al. (2015) ^[32][57] noted that, given the infrequency of building-wide evacuations requiring the use of rescue devices, a certain level of inexperience among rescuers is to be expected in a real-world scenario. Iserson (2013) ^[35][65] adds that few fire departments practice evacuating multiple non-ambulatory patients simultaneously on a routine basis. As such, recruiting untrained rescuers may represent the most realistic test data for emergency evacuation. The prevalence of rescuers not adept in the operation of rescue devices also highlights the importance of having cues within the design of devices that prompt their intended use, such as handles integrated into straps, which can facilitate their correct and efficient operation ^[32][57]. 

It is important to note that, in practice, many healthcare facilities such as small-scale hospitals either lack funding, the necessary staff resources, or the expertise to adequately purchase and conduct a mass evacuation of non-ambulatory patients using vertical evacuation devices ^[35][36][65,81]. Many hospitals are further constrained during night shifts when fewer staff are available in an emergency. 

2.4. Building Design Considerations

The tragic events of 9/11 resulted in many changes concerning emergency evacuation. One such change is a shift from a “stay put” to an “everyone out” approach, in which emergency plans are expected to provide a means for all occupants, including individuals with functional limitations, to evacuate from buildings if safe to do so ^[37][128]. As such, it is important to ensure that buildings are designed in an inclusive manner to facilitate the ability of individuals with functional limitations to independently or dependently evacuate from buildings. Individuals with visual impairments are a population that can be greatly impacted by the design of buildings, given that they need to be oriented within their environments during evacuation. Sorensen and Dederichs (2015) ^[38][84] pointed to the importance of egress paths without obstacles. At the same time, Zhang et al. (2019) ^[39][83] recommended that when paths cannot be made obstacle-free, keeping the cumulative obstacle density (defined as the ratio of the total floor area taken up by all obstacles in an evacuation zone to the total floor area in the zone) below 0.071 was recommended. In the literature, significant attention is also given to building design solutions tailored to individuals with mobility impairments. Among these articles, a clear theme is that further attention to areas of refuge for individuals with mobility impairments is needed. For instance, in McConnell and Boyce’s (2015) ^[40][75] study, 48.5% of respondents had never heard of an area of refuge in the past and only 7.9% had a full understanding of its purpose and use. A significant concern among individuals with mobility impairments regarding the use of areas of refuge is fear that they would be forgotten or that they would not receive timely communication from first responders. As a result, McConnell and Boyce (2015) ^[40][75] recommended that all areas of refuge be equipped with two-way communication systems and tools such as estimated wait time clocks. Another theme among articles focused on individuals with mobility impairments is the need to leverage elevator usage during evacuations from high-rise buildings. These elevators can either be traditional passenger elevators modified for their safe use during emergencies or dedicated fire elevators for building occupants. Traditionally, elevator use has been prohibited during fire incidents in response to concerns regarding their safe performance during a fire ^[41][42][93,129]. These concerns stem from traditional elevators being vulnerable to fire and smoke, lacking water protection, and often having no backup power ^[41][43][76,93]. Yet, the current approach of using stairs to evacuate from high floors leads to long egress times, physical and mental fatigue for evacuees, increases vulnerability due to bottlenecks and stampedes, and places individuals with mobility impairments at a grave disadvantage ^[44][130]. The change in perspective regarding building evacuation by elevators is especially noteworthy considering the growing trend of vertical cities with increasingly tall high-rise buildings ^[45][131]. Furthermore, the increase in the ageing population and chronic conditions that impact mobility prompt further exploration into safe evacuation solutions from high-rise buildings beyond stair egress. Elevators may present as an avenue for individuals with mobility impairments to evacuate without requiring assistance. Nevertheless, it is important to note that, in many parts of the world, widespread change in building design habits may be required to accommodate elevator evacuations. For instance, Taipei, Taiwan, is a populated city with a high number of residential apartments (52% are three to five floors) along with an ageing population; yet, more than 40% of them do not have elevators according to Taiwan’s Ministry of the Interior ^[46][132]. The lack of elevators in buildings presents a serious challenge for escape during an emergency such as a fire, provided they would have otherwise been able to be used safely. Until a change in building codes or building design habits occurs, an increased emphasis on efficient and cost-effective stair descent devices for high-rise buildings continues to be needed.

2.5. Strategy Solutions

While research into different evacuation devices and tools is important, it is equally valuable to evaluate strategies and logistical considerations for how to best use these devices to allow for an optimal evacuation. First, the results show that elevators can be a useful evacuation tool in high-rise buildings to decrease the evacuation time and the distance required to egress from buildings ^{[41][47][48][49]}[93,95,96,97]. Moreover, there is evidence that clogging and aggregated evacuation times for all building occupants significantly decrease when wheelchair users utilize elevators for evacuation ^[47][48][95,96]. Despite the clear benefits of elevator usage, significant education, guidance, and reassurance for individuals with functional limitations is required before, during, and after emergency evacuations to reduce anxiety and increase trust in using elevators for evacuations ^[50][51][52][92,94,107]. For instance, it is important to provide timely information to occupants that supports decision making during an emergency through digital signs and voice announcements ^[51][94]. Second, there is disagreement in the literature regarding the priority order in which hospital patients should be evacuated in case of an emergency. Rega et al. (2010) ^[53][102] recommended implementing a reverse triage approach, which prioritizes the evacuation of ambulant patients to evacuate the largest number of patients in the least amount of time. This is in contrast to the study by Zou et al. (2020) ^[54][99], which advised the priority movement of wheelchair users in order to reduce interference in movement patterns with ambulant occupants, as well as to diminish the risk of blockages and allow for the improved evacuation efficiency for both populations. Meanwhile, Childers and Taaffe (2010) ^[55][101] acknowledged the ethical and resource availability challenges of prioritizing one patient class over another. As such, they recommended using multiple evacuation teams to alternate between critical and non-critically ill patients. Third, the results highlight the importance of disseminating evacuation protocols to individuals with functional limitations prior to an evacuation. For instance, Feliciani et al. (2020) ^[56][89] found that informing wheelchair users of exit locations before an evacuation significantly reduced their evacuation time and improved surrounding crowd dynamics, decreasing congestion caused by wheelchair users unable to find accessible egress paths. The study underlines that prioritizing information provision to individuals with functional limitations may be more efficient and yield similar results compared to reaching out to the largest number of individuals possible.  Fourth, a key implication of the results is to ensure that rescue device instructions are simple and easy to follow. As discussed by Boyce et al. (2017) ^[57][90], the complexity and presentation design of stair descent device instructions, such as whether salient visual cues were used, significantly influenced the device assembly time among participants.

2.6. Training Program Solutions

2.6.1. Rescuer Training Programs

The literature suggests that conducting mock evacuation drills for rescuers leads to improved staff confidence and competency in carrying out an emergency evacuation ^[58][59][60][108,110,111]. VanDevanter et al. (2017) ^[59][110] emphasized the need for more hands-on tabletop exercises as opposed to lecture-based training. The results also advise familiarizing rescuers with different evacuation equipment and improving communication with triage leaders at the time of an emergency ^[58][61][108,133]. While yearly drills are most common among organizations, it has been suggested that knowledge decay following evacuation training begins at approximately 3 months, and more frequent training may be required ^[62][109]. Nevertheless, a significant challenge reported is managing staff unavailability during training sessions and maintaining interest among busy staff members who need to quickly return to their duties and other obligations ^[58][108]. On that front, virtual reality technology has been suggested as an effective alternative to conventional methods of training. Virtual simulation training not only leads to improved disaster preparedness and communication as compared to lecture-based training; it also does not share the challenge of needing to train a large number of staff at the same time ^[61][62][109,133]. The findings also emphasize the need to improve the knowledge of staff in public facilities on building accessibility and to be able to effectively communicate that information to individuals with functional limitations ^[23][30]. As stated in Lena et al.’s (2012) ^[23][30] study, a common fear among study participants was not knowing whether a building was accessible before arriving at the facility. By training staff to provide this information along with any evacuation safety plans on a timely basis, a significant barrier to accessibility can be eliminated. One way to provide this training is by conducting an evacuation drill for staff members with individuals with functional limitations present, in order for staff to grasp how safe evacuation from a building can be adapted to different functional limitations ^[23][30]. 

2.6.2. Rescuee Training Programs

The rescuee subsection contained articles covering a wide variety of functional limitations, including children with complex health needs, individuals with mental health impairments, older adults, and individuals with mobility impairments. A recurring theme that emerged is that individuals with different functional limitations may require different training programs according to their needs and challenges when preparing for an emergency. For instance, some individuals with past traumatic exposure to disasters have been shown to not engage in risk reduction, despite completing general emergency preparedness training ^[63][64][134,135]. Another point of discussion among the articles was determining who would be most suitable to deliver emergency preparedness programs. Most articles proposed leveraging current touchpoints with the population at hand. For instance, Twyman et al. (2014) ^[65][118] proposed recruiting primary care nurses to support older adults in developing fire escape plans in the home environment. Meanwhile, Casteel et al. (2020) ^[66][116] recruited firefighters given that they are perceived as trustworthy among the general public and are in frequent contact with older adults through fire safety outreach efforts. There was also discussion of determining the most suitable intervention for improving emergency preparedness. 

2.7. Emergency Types and Extreme Weather Events

Of the 30 articles that tailored their research to a specific emergency type, only five addressed evacuation solutions other than fire emergencies (i.e., large disasters, hurricanes, earthquakes, landslides). While preparing for fire emergencies is important, more work is needed to consider evacuations during other types of emergencies, including floods, power outages, terrorism threats, chemical or radiation leaks, or other extreme weather events. This area of future research is especially relevant when considering that extreme meteorological events may be increasing as a result of climate change ^[12][13][12,13]. It may also be useful to investigate how emergency types should be handled that require less urgency to evacuate individuals quickly while still requiring egress, such as power outages and floods.

2.8. Recommendations

4.8.1. Notification Solution Recommendations

• Continue to tailor the design and implementation of notification solutions according to the needs of individuals with different impairments including older adults and individuals with hearing loss. Solutions that target other impairments, including autism spectrum disorder, anxiety, or cognitive impairments remain largely absent.
• Consider solutions for building types that may require specialized engineering considerations in terms of notification approaches, such as correctional facilities and indoor stadiums.

4.8.2. Wayfinding Solution Recommendations

• Test wayfinding solutions in real-world environments, accounting for the interaction of individuals with functional limitations with crowds and first responders. Also, consider the impact of the use of wayfinding apps by the general public on overall evacuee safety and crowd dynamics.
• Employ a user-centred approach to wayfinding solutions, accounting for the unique needs and behaviours of individuals with functional limitations as they organically navigate buildings. An example of a population that would benefit from future research with regard to unique wayfinding solutions is individuals with cognitive impairments.
• Consider how effective wayfinding and egress solutions can overcome challenges associated with old or complex building types not designed for accessible egress.

2.8.3. Egress Solution Recommendations

• Conduct more hospital-focused studies in a simulated or real-world environment, considering the impact of evacuation devices on the flow dynamics of other evacuees and first responders. Consider nuances present in a real emergency, such as the rescue device preparation time, psychological and physiological stress factors present in an emergency setting, and the effect of poorly lit stairwells.
• Include the participation of both rescuers and rescuees in emergency evacuation planning and the assessment of optimal rescue devices. Further research should also continue to propose cost-effective evacuation devices that do not negatively impact the physical demands of the rescuer and the safety of the rescuee.
• Consider the differences in descending versus ascending to an exit and how different rescue devices may be needed.

2.8.4. Building Design Recommendations

• Complete further validation of the relationship between obstacle density and the ability of individuals with visual impairments to evacuate from buildings.
• Explore the potential of revising building codes to facilitate the integration of elevators that can be safely used by individuals with functional limitations during emergencies, including fires (see accompanied strategy recommendations below).
• Continue to pursue studies that consider egress from unique or structurally complex building types relevant to different regions of the world.

2.8.5. Strategy Recommendations

• While current technological limitations do not restrict evacuation by elevators during emergencies, further attention on strategies surrounding their use continues to be needed before they can be safely used.
  • Conduct further research to clarify optimal elevator priority strategies in case of an emergency, tailored according to building type, building height, building occupant demographics, or other situations as needed. Consider how these priority strategies can be enforced in a stressful evacuation setting through real-world simulations or other means.
  • Explore methods to manage the risk of elevator overcrowding or extended wait times during emergencies.
  • Further assess the use of elevators for evacuation in hospitals, given that most studies focused on high-rise buildings.
  • Conduct more real-world studies assessing elevator use and strategies, as opposed to just computer simulations and end-user interviews.
• Establish consensus and general guidelines for patient egress priority order during hospital evacuations. Consider how these guidelines can be combined with the strategic arrangement of patients in healthcare facilities.
• Explore how the effective design of instructions and maps could be applied for other aspects of an evacuation, such as adhering to elevator priority measures and fire escape plans.

2.8.6. Training Program Recommendations

• Assess the use of training programs for rescuers in a diverse range of building types, given that most studies focused on staff in hospitals.
• Conduct further research to compare and rank different interventions (i.e., training programs, disaster supply kits, etc.) and distribution mediums (i.e., primary care visits, home visits) to improve emergency preparedness for different populations with functional limitations.