FEMA 453 / May 2006
Risk Management Series
Safe Rooms and Shelters
Protecting People Against Terrorist Attacks 

Chapter 1 Design Considerations

1.1 Overview

The attack against the Alfred P. Murrah Federal Office Building in Oklahoma City 
and the anthrax attacks in October 2001 made it clear that chemical, biological, 
radiological, and explosive (CBRE) attacks are a credible threat to our society. 
Such attacks can cause a large number of fatalities or injuries in high-
occupancy buildings (e.g., school buildings, hospitals and other critical care 
facilities, nursing homes, day-care centers, sports venues, theaters, and 
commercial buildings) and residential neighborhoods.

This chapter discusses the potential manmade threats to 
which a shelter may be exposed and the level of protection (LOP) that may be 
assumed by building owners when deciding to build a shelter to support the 
preparedness objectives established in the National Preparedness Goal. This 
guidance complements other shelter publications such as the American Red Cross 
(ARC) 4496, Standards for Hurricane Evacuation Shelter Selection; FEMA 320, 
Taking Shelter From the Storm: Building a Safe Room Inside Your House; and FEMA 
361, Design and Construction Guidance for Community Shelters.

This manual presents information about the design and construction of shelters 
in the work place, home, or community building that will provide protection in 
response to the manmade CBRE threats as defined in the National Response Plan 
(NRP) and the National Planning Scenarios. As published in the National 
Preparedness Guidance (April 2005), the Federal interagency community developed 
15 planning scenarios (the National Planning Scenarios or Scenarios) for use in 
national, Federal, state, and local homeland security preparedness activities. 
The National Planning Scenarios are planning tools and are representative of the 
range of potential terrorist attacks and natural disasters and the related 
impacts that face our nation. The scenarios establish the range of response 
requirements to facilitate preparedness planning.

The National Planning Scenarios describe the potential scope and magnitude of 
plausible major events that require coordination among various jurisdictions and 
levels of government and communities.

Scenario 1: Nuclear Detonation  10-Kiloton Improvised Nuclear Device
Scenario 2: Biological Attack  Aerosol Anthrax
Scenario 3: Biological Disease Outbreak  Pandemic Influenza
Scenario 4: Biological Attack  Plague
Scenario 5: Chemical Attack  Blister Agent
Scenario 6: Chemical Attack  Toxic Industrial Chemicals
Scenario 7: Chemical Attack  Nerve Agent
Scenario 8: Chemical Attack  Chlorine Tank Explosion
Scenario 9: Natural Disaster  Major Earthquake
Scenario 10: Natural Disaster  Major Hurricane
Scenario 11: Radiological Attack  Radiological Dispersal Devices
Scenario 12: Explosives Attack  Bombing Using Improvised Explosive Device
Scenario 13: Biological Attack  Food Contamination
Scenario 14: Biological Attack  Foreign Animal Disease (Foot and Mouth Disease)
Scenario 15: Cyber Attack

Manmade threats include threats of terrorism, technological accidents, 
assassinations, kidnappings, hijackings, and cyber attacks (computer-based), and 
the use of CBRE weapons. High-risk targets include military and civilian 
government facilities, international airports, large cities, and high-profile 
landmarks. Terrorists might also target large public gatherings, water and food 
supplies, utilities, and corporate centers. Further, they are capable of 
spreading fear by sending explosives or chemical and biological agents through 
the mail.

This chapter also considers shelter design concepts that relate to the type of 
shelter being designed and where it may be located. It discusses how shelter use 
(either single or multiple) may affect the type of shelter selected and the 
location of that shelter on a particular site. The chapter describes key 
operations zones in and around a shelter that need to be taken into 
consideration as a means to provide safe ingress and egress and medical 
assistance to victims of a manmade event (terrorist attack or technological 
accident). The decision to enter a shelter is made by the senior management 
staff based on notification of a credible threat or as a result of an actual 
disaster. The National Incident Management System (NIMS) and the Catastrophic 
Incident Supplement (CIS) to the NRP established the procedures to respond to 
and recover from a CBRE event. Section 4.2 discusses the plans alerting and 
notification, and response and recovery processes. The objective of this chapter 
is to provide a broad vision on how a shelter should be designed to protect 
against catastrophic events.

The decision to design and construct a shelter can be based on a single factor 
or on a collection of factors. Single factors are often related to the potential 
for loss of life or injury (e.g., a hospital that cannot move patients housed in 
an intensive care unit decides to build a shelter, or shelters, within the 
hospital; a school decides not to chance fate and constructs a shelter). A 
collection of factors could include the type of hazard event, probability of 
event occurrence, severity of the event, probable single and aggregate annual 
event deaths, shelter costs, and results of computer models that evaluate the 
benefits and costs of the shelter project.

1.2 Potential Threats

Rather than identify a specific threat, this document provides general guidance 
that will address different types of building construction and the reasonable 
mitigative measures to provide a secure shelter. However, it is important for 
building owners and design professionals to understand the potential threats to 
which buildings may be exposed. This section provides an overview of manmade 
threats.

The term threat is typically used to describe the design criteria for manmade 
disasters (technological accident) or terrorism. Identifying the threats for 
manmade threats can be a difficult task. Because they are different from other 
natural hazards such as earthquakes, floods, and hurricanes, manmade threats are 
difficult to predict. Many years of historical and quantitative data, and 
probabilities associated with the cycle, duration, and magnitude of natural 
hazards exist. The fact that data for manmade threats are scarce and that the 
magnitude and recurrence of terrorist attacks are almost unpredictable makes the 
determination of a particular threat for any specific site or building difficult 
and largely subjective. Such asymmetrical threats do not exclusively target 
buildings and may employ diversionary tactics to actually direct occupants to a 
primary attack instrument.

With any manmade threat, it is important to determine who has the intent to 
cause harm. The aggressors seek publicity for their cause, monetary gain (in 
some instances), or political gain through their actions. These actions can 
include injuring or killing people; destroying or damaging facilities, property, 
equipment, or resources; or stealing equipment, material, or information.
Aggressor tactics run the gamut: moving vehicle bombs; stationary vehicle 
bombs; bombs delivered by persons (suicide bombers); exterior attacks (thrown 
objects like rocks, Molotov cocktails, hand grenades, or hand-placed bombs); 
stand-off weapons attacks (rocket propelled grenades, light antitank weapons, 
etc.); ballistic attacks (small arms and high power rifles); covert entries 
(gaining entry by false credentials or circumventing security with or without 
weapons); mail bombs (delivered to individuals); supply bombs (larger bombs 
processed through shipping departments); airborne contamination (CBR agents used 
to contaminate the air supply of a building); and waterborne contamination (CBR 
agents injected into the water supply). This section focuses on explosive 
threats, chemical agents, biological warfare agents, and radiological attacks. 

1.2.1 Explosive Threats

The explosive threat is particularly insidious, because all of the ingredients 
required to assemble an improvised explosive device are readily available at a 
variety of farm and hardware stores. The intensity of the explosive detonation 
is limited by the expertise of the person assembling the device and the means of 
delivery. Although the weight of the explosive depends on the means of 
transportation and delivery, the origin of the threat depends primarily on the 
access available to the perpetrator. Operational security procedures will define 
the areas within or around a building at which a device may be located, 
undetected by the building facilities staff. These security procedures include 
screening of vehicles, inspection of delivered parcels, and vetting hand carried 
bags. The extent to which this inspection is carried out will determine the size 
of an explosive device that may evade detection. Despite the most vigilant 
attempts, however, it is unrealistic to expect complete success in preventing a 
small threat from evading detection. Nevertheless, it is unlikely that a large 
threat may be brought into a building. As a result, a parcel sized device may be 
introduced into publicly accessible lobbies, garages, loading docks, cafeterias, 
or retail spaces and it must be assumed that a smaller explosive device may be 
brought anywhere into the building.

Although operational security measures can drastically limit the size of the 
explosive device that could be introduced onto a building site, there is no 
means of limiting the size of the explosive that could be contained within a 
vehicle traveling on the surrounding streets or roadways.

Explosives weigh approximately 100 pounds per cubic foot and, as a result, the 
maximum credible threat corresponds to the weight of explosives that can be 
packaged in a variety of containers or vehicles. The Department of Defense (DoD) 
developed a chart to help indicate the weight of explosives and deflagrating 
materials that may reasonably fit within a variety of containers and vehicles 
(see Table 1-1). The table also indicates the safe evacuation distances for 
occupants of conventional unreinforced buildings, based on their ability to 
withstand severe damage or resist collapse. Similarly, Table 1-1 indicates the 
safe evacuation distance for pedestrians exposed to explosive effects based on 
the greater of fragment throw distance or glass breakage/falling glass hazard 
distance. Because a pipe bomb, suicide belt/vest, backpack, and 
briefcase/suitcase bomb are specifically designed to throw fragments, protection 
from these devices may require greater safe evacuation distances than an equal 
weight of explosives transported in a vehicle. Table 1-2 shows safe evacuation 
distances for liquefied petroleum gas (LPG) threats.

[Begin Table 1-1]
Table 1-1: Safe Evacuation Distances from Explosive Threats

Threat Description: Pipe Bomb
Explosives Mass* (TNT equivalent) 
 5 lbs
 2.3 kg
Building Evacuation Distance** 
 70 ft
 21 m
Outdoor Evacuation Distance***
 850 ft
 259 m
 
Threat Description: Suicide Belt
Explosives Mass* (TNT equivalent)
 10 lbs
 4.5 kg
Building Evacuation Distance**
 90 ft
 27 m
Outdoor Evacuation Distance***
 1,080 ft
 330 m
 
Threat Description: Suicide Vest
Explosives Mass* (TNT equivalent)
 20 lbs
 9 kg
Building Evacuation Distance**
 110 ft
 34 m
Outdoor Evacuation Distance***
 1,360 ft
 415 m

Threat Description: Briefcase/Suitcase Bomb
Explosives Mass* (TNT equivalent)
 50 lbs
 23 kg
Building Evacuation Distance**
 150 ft
 46 m
Outdoor Evacuation Distance***
 1,850 ft
 564 m
 
Threat Description: Compact Sedan
Explosives Mass* (TNT equivalent)
 500 lbs
 227 kg
Building Evacuation Distance**
 320 ft
 98 m
Outdoor Evacuation Distance***
 1,500 ft
 457 m
 
Threat Description: Sedan
Explosives Mass* (TNT equivalent)
 1,000 lbs
 454 kg
Building Evacuation Distance**
 400 ft
 122 m
Outdoor Evacuation Distance***
 1,750 ft
 534 m
 
Threat Description: Passenger/Cargo Van
Explosives Mass* (TNT equivalent)
 4,000 lbs
 1,814 kg
Building Evacuation Distance**
 640 ft
 195 m
Outdoor Evacuation Distance***
 2,750 ft
 838 m
 
Threat Description: Small Moving Van/Delivery Truck
Explosives Mass* (TNT equivalent)
 10,000 lbs
 4,536 kg
Building Evacuation Distance**
 860 ft
 263 m
Outdoor Evacuation Distance***
 3,750 ft
 1,143 m
 
Threat Description: Moving Van/Water truck
Explosives Mass* (TNT equivalent)
 30,000 lbs
 13,608 kg
Building Evacuation Distance**
 1,240 ft
 375 m
Outdoor Evacuation Distance***
 6,500 ft
 1,982 m
 
Threat Description: Semi-trailer
Explosives Mass* (TNT equivalent)
 60,000 lbs
 27,216 kg
Building Evacuation Distance**
 1,570 ft
 475 m
Outdoor Evacuation Distance***
 7,000 ft
 2,134 m

* Based on the maximum amount of material that could reasonably fit into a 
container or vehicle. Variations are possible.
** Governed by the ability of an unreinforced building to withstand severe 
damage or collapse.
*** Governed by the greater of fragment throw distance or glass breakage/falling 
glass hazard distance. These distances can be reduced for personnel wearing 
ballistic protection. Note that the pipe bombs, suicide belts/vests, and 
briefcase/suitcase bombs are assumed to have a fragmentation characteristic that 
requires greater stand-off distances than an equal amount of explosives in a 
vehicle.
[End Table 1-1]

[Begin Table 1-2]
Table 1-2: Safe Evacuation Distances from LPG Threats

Threat Description: Small LPG Tank
LPG Mass/Volume
 20 lbs/5 gal
 9 kg/19 l
Fireball Diameter*
 40 ft
 12 m
Safe Distance**
 160 ft
 48 m
 
Threat Description: Large LPG Tank
LPG Mass/Volume
 100 lbs/25 gal
 45 kg/95 l
Fireball Diameter*
 69 ft
 21 m
Safe Distance**
 276 ft
 84 m
 
Threat Description: Commercial/Residential LPG tank
LPG Mass/Volume
 2,000 lbs/500 gal
 907 kg/1,893 l
Fireball Diameter*
 184 ft
 56 m
Safe Distance**
 736 ft
 224 m
 
Threat Description: Small LPG Truck
LPG Mass/Volume
 8,000 lbs/2,000 gal
 3,630 kg/7,570 l
Fireball Diameter*
 292 ft
 89 m
Safe Distance** 
 1,168 ft
 356 m
 
Threat Description: Semi-tanker LPG
LPG Mass/Volume
 40,000 lbs/10,000 gal
 18,144 kg/37,850 l
Fireball Diameter*
 499 ft
 152 m
Safe Distance**
 1,996 ft
 608 m
 
* Assuming efficient mixing of the flammable gas with ambient air.
** Determined by U.S. firefighting practices wherein safe distances are 
approximately four times the flame height. Note that an LPG tank filled with 
high explosives would require a significantly greater stand-off distance than if 
it were filled with LPG.
[End Table 1-2]

The Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) report on 
Incidents, Casualties and Property Damage for all states for 2002 lists 553 
actual bombing incidents, 32 of which were premature explosions, injuring 80 
people, killing 13, and causing over $5 million in damages. Nearly half of the 
events were against buildings and nearly a quarter were against vehicles.
Only two domestic terrorist bombings involved the use of large quantities of 
High Energy explosive materials. (For more information on High Energy 
explosives, see FEMA 426, Reference Manual to Mitigate Potential Terrorist 
Attacks Against Buildings, Chapter 4.) Although these events represent the 
largest explosions that have occurred to date, they do not accurately represent 
the actual domestic explosive threat. The 1995 explosion that collapsed portions 
of the Murrah Federal Office Building in Oklahoma City contained 4,800 pounds of 
ammonium nitrate and fuel oil (ANFO) and the 1993 explosion within the parking 
garage beneath the World Trade Center complex contained 1,200 pounds of urea 
nitrate.

Every year, approximately 1,000 intentional explosive detonations are reported 
by the Federal Bureau of Investigation (FBI) Bomb Data Center. As implied by the 
FBI statistics, the majority of the domestic events contain significantly 
smaller weights of Low Energy explosives. (For more information on Low Energy 
explosives, see FEMA 426, Chapter 4.) Figure 1-1 illustrates the breakdown of 
domestic terrorist events from 1980 to 2001. The vast majority of the 294 
terrorist incidents, 55 suspected terrorist incidents, or 133 prevented 
terrorist incidents, involved explosives and 75 percent of these events occurred 
in the 1980s. The explosive that was used in the 1996 pipe bomb attack at the 
Olympics in Atlanta, Georgia, consisted of smokeless powder and was preceded by 
a warning that was called in 23 minutes before the detonation.

Figure 1-1: Terrorism by event 1980 through 2001. A chart showing:
324 Bombings
33 Arsons
22 Other
21 Assassinations
19 Shootings
19 Sabotage/Malicious Destruction
15 Robberies
10 Hostile Takeovers
6 Assaults
6 WMD
3 Hijackings/Aircraft Attacks
2 Kidnappings
2 Rocket Attacks
482 Total Incidents or Planned Attacks
Source: FBI Terrorism 2000/2001 Publication #308

Although the majority of these explosions targeted residential properties and 
vehicles, 63 took place in educational facilities, causing a total of $68,500 in 
property damage. By contrast, other than the attack against the Murrah Federal 
Office Building, no explosive devices were detonated at a Federal government 
owned facility, and only nine were detonated at local/state government 
facilities. Nearly 80 percent of the people known to be involved in bombing 
incidents were young offenders, and less than  percent of the perpetrators 
were identified as members of terrorist groups. Vandalism was the motivation in 
53 percent of the known intentional and accidental bombing incidents, and the 
timing of the attacks was fairly uniformly distributed throughout the day. 
Nevertheless, the protective design of structures focuses on the effects of High 
Energy explosives and relates the different mixtures to an equivalent weight of 
trinitrotoluene (TNT).

1.2.2	CBR Attacks

Like explosive threats, CBR threats may be delivered externally or internally to 
the building. External ground-based threats may be released at a stand-off 
distance from the building or may be delivered directly through an air intake or 
other opening. Interior threats may be delivered to accessible areas such as the 
lobby, mailroom, or loading dock, or they may be released into a secure area 
such as a primary egress route. There may not be an official or obvious warning 
prior to a CBR event. Although official warnings should always be heeded, the 
best defense may be to be alert to signs of a release.
There are three potential methods of attacks in terms of CBR:

- A large exterior release originating some distance away from the building 
(includes delivery by aircraft)

- A small localized exterior release at an air intake or other opening in the 
exterior envelope of the building

- A small interior release in a publicly accessible area, a major egress route, 
or other vulnerable area (e.g., elevator lobby, mail room, delivery, receiving 
and shipping, etc.)

Chapter 4 provides additional guidance on emergency management considerations 
that may have an impact on siting or design of a shelter.

1.2.2.1 Chemical	Agents. Toxic chemical agents can present airborne hazards 
when dispersed as gases, vapors, or solid or liquid aerosols. Generally, 
chemical agents produce immediate effects, unlike biological or radiological 
agents. In most cases, toxic chemical agents can be detected by the senses, 
although a few are odorless. Their effects occur mainly through inhalation, 
although they can also cause injury to the eyes and skin.

1.2.2.2 Biological Warfare Agents. Biological warfare agents are organisms or 
toxins that can kill or incapacitate people and livestock, and destroy crops. 
The three basic groups of biological agents that would likely be used as weapons 
are bacteria, viruses, and toxins. 

- Bacteria. Bacteria are small free-living organisms that reproduce by simple 
division and are easy to grow. The diseases they produce often respond to 
treatment with antibiotics.

- Viruses. Viruses are organisms that require living cells in which to reproduce 
and are intimately dependent upon the body they infect. The diseases they 
produce generally do not respond to antibiotics; however, antiviral drugs are 
sometimes effective. 

- Toxins. Toxins are poisonous substances found in, and extracted from, living 
plants, animals, or microorganisms; some toxins can be produced or altered by 
chemical means. Some toxins can be treated with specific antitoxins and selected 
drugs.

Most biological agents are difficult to grow and maintain. Many break down 
quickly when exposed to sunlight and other environmental factors, while others 
such as anthrax spores are very long lived. They can be dispersed by spraying 
them in the air or by infected animals that carry the disease, as well through 
food and water contamination:

- Aerosols. Biological agents are dispersed into the air, forming a fine mist 
that may drift for miles. Inhaling the agent may cause disease in people or 
animals. 

- Animals. Some diseases are spread by insects and animals, such as fleas, 
flies, mosquitoes, and mice. Deliberately spreading diseases through livestock 
is also referred to as agroterrorism.

- Food and water contamination. Some pathogenic organisms and toxins may persist 
in food and water supplies. Most microbes can be killed, and toxins deactivated, 
by cooking food and boiling water.

Person-to-person spread of a few infectious agents is also possible. Humans have 
been the source of infection for smallpox, plague, and the Lassa viruses.

[Begin text Box]
Anthrax spores formulated as a white powder were mailed to individuals in the 
Federal Government and media in the fall of 2001. Postal sorting machines and 
the opening of letters dispersed the spores as aerosols. Several deaths 
resulted. The effect was to disrupt mail service and to cause a widespread fear 
of handling delivered mail among the public.
[End text box]

Figure 1-2: Sample anthrax letter
Source: FBI Terrorism 2000/2001 Publication #308

1.2.2.3 Radiological Attacks. Shelters described in this manual do not address 
the severe and various effects generated by nuclear events, including blinding 
light, intense heat (thermal radiation), initial nuclear radiation, blast, fires 
started by the heat pulse, and secondary fires caused by the destruction. 
Protection against these severe effects of a nuclear explosion is not considered 
in this manual.

Terrorist use of a radiological dispersion device (RDD), often called dirty 
nuke or dirty bomb, is considered far more likely than use of a nuclear 
device. These radiological weapons are a combination of conventional explosives 
and radioactive material designed to scatter dangerous and sublethal amounts of 
radioactive material over a general area. Such radiological weapons appeal to 
terrorists because they require very little technical knowledge to build and 
deploy compared to that of a nuclear device. Also, these radioactive materials, 
used widely in medicine, agriculture, industry, and research, are much more 
readily available and easy to obtain compared to weapons grade uranium or 
plutonium. Figure 1-3 shows the number of incidents of radioactive materials 
smuggling from 1993 to 2003. 

There is no way of knowing how much warning time there would be before an attack 
by a terrorist using a radiological weapon. A surprise attack remains a 
possibility.

[Begin figure]
Figure 1-3: Radioactive materials smuggling

Radioactive Smuggling
Smuggling of potential ingredients for a dirty bomb is on the increase, but 
there are fewer incidents involving fissile materials that could be used for 
making a nuclear bomb.

Graph showing the number of incidents ranging from 0 to 60 from the year 1993 
through 2003 for both Fissile Material and Other Radioactive Material.

SOURCE: International Atomic Energy Agency
[End figure]

1.3 Levels of Protection 

Currently, there are only two Federal standards that have been promulgated for 
Federal facilities that define LOPs for manmade threats: the Interagency 
Security Committee (ISC) Design Criteria and the DoD Minimum Antiterrorism 
Standards, UFC 4-010-01. Both standards address blast primarily through the use 
of stand-off distance and ensuring walls and glazing blast pressures are 
strengthened to withstand the blast shock wave. Both standards address CBR 
agents primarily through the use of filtration, emergency shutdown of mechanical 
and electrical systems, and mass notification to building occupants.
Until the building, mechanical, electrical, and life safety codes are 
promulgated for manmade events, the ISC building standards provide a reasonable 
approach to selecting a level of protection for a shelter for CBR agents.

1.3.1	Blast Levels of Protection

The level of protection in response to blast loading defines the extent of 
damage and debris that may be sustained in response to the resulting blast 
pressures and impulses. (For more information on blast pressure impulses, see 
FEMA 426, Chapter 4.) The levels of protection are generally defined in the 
terms of performance. Fundamental to the discussion of levels of protection is 
the notion of repairable damage. Repair is typically assumed to be within days 
to weeks and the structure requires partial evacuation during repairs. Table 1-3 
provides a synopsis of the ISC blast standards.

[Begin Table 1-3]
Table 1-3: Correlation of ISC Levels of Protection and Incident Pressure to 
Damage and Injury

Level of Protection: Minimum and Low 
Potential Structural Damage: The facility or protected space will sustain a high 
level of damage without progressive collapse. Casualties will occur and assets 
will be damaged. Building components, including structural members, will require 
replacement, or the facility may be completely unrepairable, requiring 
demolition and replacement.

Potential Glazing Hazards:
- For Minimum Protection, there are no restrictions on the type of glazing used.
- For Low Protection, there is no requirement to design windows for specific 
blast pressure loads. However, the use of glazing materials and designs that 
minimize the risks is encouraged.
- Glazing cracks and window system fails catastrophically. Fragments enter 
space, impacting a vertical witness panel at a distance of no more than 3 m (10 
ft) from the window at a height greater than 0.6 m (2 ft) above the floor.
 
Level of Protection: Medium 
Potential Structural Damage: Moderate damage, repairable. The facility or 
protected space will sustain a 
significant degree of damage, but the structure will be reusable. Some 
casualties may occur and assets may be damaged. Building elements other than 
major structural members may require replacement.

Potential Glazing Hazards:
- For Medium and High Protection, design up to the specified load as directed by 
the risk assessment. Window systems design (glazing, frames, anchorage to 
supporting walls, etc.) on the exterior faade should be balanced to mitigate 
the hazardous effects of flying glazing following an explosive event. The walls, 
anchorage, and window framing should fully develop the capacity of the glazing 
material selected.
- Glazing cracks. Fragments enter space and land on the floor and impact a 
vertical witness panel at a distance of no more than 3 m (10 ft) from the window 
at a height greater than 0.6 m (2 ft) above the floor.
 
Level of Protection: High
Potential Structural Damage: Minor damage, repairable. The facility or protected 
space may globally sustain minor damage with local significant damage possible. 
Occupants may incur some injury, and assets receive minor damage.

Potential Glazing Hazards:
- For Medium and High Protection, design up to the specified load as directed by 
the risk assessment. Window systems design (glazing, frames, anchorage to 
supporting walls, etc.) on the exterior faade should be balanced to mitigate 
the hazardous effects of flying glazing following an explosive event. The walls, 
anchorage, and window framing should fully develop the capacity of the glazing 
material selected.
- Glazing cracks. Fragments enter space and land on the floor no farther than 3 
m (10 ft) from the window.
[End Table 1-3]

1.3.2	CBR Levels of Protection

Protection against airborne chemical, biological, and radiological (CBR) agents 
or contaminants is typically achieved by using particulate and adsorption 
filters, and personal protective equipment (PPE). Many different types of 
filters are available for CBR releases. Filter efficiency (e.g., how well the 
filter captures the toxic material) varies based on the filter type (e.g., 
activated or impregnated charcoal) and the specific toxic material. No single 
filter can protect against all CBR materials; therefore, it is important to 
verify which CBR materials a filter protects against.

There are three levels of protection that range from filtration with 
pressurization (Class 1), filtration with little or no pressurization (Class 2), 
and passive protection (Class 3). Class 1 protection is for a large-scale 
release over an extended period of time and would apply to mission essential 
government and commercial buildings that must remain operational 24 hours a 
day/7 days a week. Class 2 protection is for a terrorist attack or technological 
accident with little or no warning and is characterized as a short duration 
small scale release. Class 3 is typically applicable to an industrial accident 
that results in a short duration release. These three levels of protection are 
discussed in greater detail in Chapter 3. Table 1-4 provides a synopsis of the 
ISC CBR protection standards. 

[Begin text box]
The CBR levels of protection included in this section are consistent with the 
Department of Homeland security (DHS) Working Group on Radiological Dispersal 
Device Preparedness and the Health Physics Societys (HPSs) scientific and 
Public Issues Committee reports:

Sheltering is 10-80% effective in reducing dose depending upon the duration of 
exposure, building design and ventilation. If there is a passing plume of 
radioactivity, sheltering may be preferable to evacuation. When sheltering, 
ventilation should be turned off to reduce influx of outside air. Sheltering may 
not be appropriate if doses are projected to be very high or long in duration.

Sheltering is likely to be more protective than evacuation in responding to a 
radiological terrorist event. Therefore, the HPS recommends that sheltering be 
the preferred protective action. The Protective action guidance (PAG) for 
sheltering is the same as the existing evacuation PAG, i.e., 10 mSv (1 rem), 
with the minimum level for initiation being the same as the existing PAG, i.e., 
1 mSv (100 mrem).
[End text box]

[Begin Table 1-4]
Table 1-4: ISC CBR Levels of Protection

Level of Protection: Low 
For Biological/Radiological Contaminants: Use minimum efficiency reporting value 
(MERV) 13 filter or functional equivalent.
For Chemical/Radiological: None
Additional Considerations: None
Class: 3

Level of Protection: Medium 
For Biological/Radiological Contaminants: Use high-efficiency particulate air 
(HEPA) filter or functional equivalent.
For Chemical/Radiological; Use gas absorber for outside air.
Additional Considerations: 
- Design for future detection technology
- Stairway pressurization system should maintain positive pressure in stairways 
for occupant refuge, safe evacuation, and access by firefighters. The entry of 
smoke and hazardous gases into stairways must be minimized.
- Locate utility systems at least 15 m (50 ft) from loading docks, front 
entrances, and parking areas. 
Class: 2

Level of Protection: High 
For Biological/Radiological Contaminants: Use HEPA filter or functional 
equivalent.
For Chemical/Radiological: Use gas absorber for outside air and return air.
Additional Considerations
- Design for future detection technology
- Stairway pressurization system should maintain positive pressure in stairways 
for occupant refuge, safe evacuation, and access by firefighters. The entry of 
smoke and hazardous gases into stairways must be minimized.
- Locate utility systems at least 15 m (50 ft) from loading docks, front 
entrances, and parking areas.
Class: 1, 2
[End Table 1-4]

1.4 Shelter Types

A CBRE shelter can be designed as a standalone or internal shelter to be used 
solely as a shelter or to have multiple purposes, uses, or occupancies. This 
section provides a series of definitions that can be useful when deciding to 
build a new shelter or upgrade an existing shelter.

1.4.1	Standalone Shelters

A standalone shelter is considered a separate building (i.e., not within or 
attached to any other building) that is designed and constructed to withstand 
the range of natural and manmade hazards. This type of shelter has the following 
characteristics:

- It may be sited away from potential debris hazards.

- It will be structurally and mechanically separate from any building and 
therefore not vulnerable to being weakened if part of an adjacent structure 
collapses or if a CBRE event occurs in the adjacent building.

- It does not need to be integrated into an existing building design.

A shelter for CBRE protection may be as simple as an interior residential room 
to the traditional public shelter able to support several hundred people. The 
number of persons taking refuge in a shelter will typically be more than 12 and 
could be up to several hundred or more. 

1.4.2 Internal Shelters

An internal shelter is a specially designed and constructed room or area within 
or attached to a larger building that is designed and constructed to be 
structurally independent of the larger building and to withstand the range of 
natural and manmade hazards. It shows the following characteristics:

- It is partially shielded by the surrounding building and may not experience 
the full force of the blast. (Note that any protection provided by the 
surrounding building should not be considered in the shelter design.)

- It is designed to be within a new building and may be located in an area of 
the building that the building occupants can reach quickly, easily, and without 
having to go outside, such as a data center, conference room, gymnasium, or 
cafeteria.

- It may reduce the shelter cost because it is typically part of a planned 
renovation or building project.

1.4.3	Shelter Categories

A standalone or internal shelter may serve as a shelter only, or it may have 
multiple uses (e.g., a multi-use shelter at a school could also function as a 
classroom, lunchroom, or laboratory; a multi-use shelter intended to serve a 
manufactured housing community or single-family-home subdivision could also 
function as a community center). The decision to design and construct a single-
use or a multi-use shelter will likely be made by the prospective client or the 
owner of the shelter. To help the designer respond to non-engineering and non-
architectural needs of shelter owners, this section discusses different shelter 
categories and usages. Table 1-5 provides a summary of the commercial shelter 
categories.

[Begin Table 1-5]
Table 1-5: Commercial Shelter Categories

Shelter Considerations: Level of Protection
In-Ground: Blast  Medium, CBR  class 3
Single-Use: Blast  Low, CBR  class 3
Multi-Use: All
Community: All
 
Shelter Considerations: Expected Capacity
In-Ground: 1-100
Single-Use: 1-10
Multi-Use: 1-100
Community: 100-1,000
 
Shelter Considerations: Location
In-Ground: Basement or sub-basement area without windows and semi-hardened walls 
and ceiling
Single-Use: Interior space without windows and semi-hardened walls and ceiling
Multi-Use: Conference Room, Data Center, Bathroom, Stairwell, Elevator Core
Community: School, Church, Mall, Government Building
 
Shelter Considerations: Special Considerations
In-Ground: Difficult to site/build in high water table and rocky areas 
Single-Use:  Annual or semi-annual inspection and rotation of supplies
Multi-Use: May need multiple areas in large buildings and commercial office 
space; plan and exercises to prevent overcrowding
Community: Plan for multi-lingual, elderly, non-ambulatory, and special needs 
populations
 Life safety NFPA 101 and 5000 guidance
 ADA compliance

NFP = National Fire Protection Association
ADA = Americans with Disabilities Act
[End Table 1-5]

- In-ground shelters. The in-ground shelters referred to in this manual are 
built below ground inside a building and therefore can be entered directly from 
within the building. Other types of in-ground shelters are available that are 
designed to be installed outside a building and entering one of these exterior 
in-ground shelters would require leaving the building. 

- Single-use shelters. Single-use shelters are used only in the event of a 
hazard event. One advantage of single-use shelters is a potentially simplified 
design that may be readily accepted by the authority having local jurisdiction. 
These shelters typically have simplified electrical and mechanical systems 
because they are not required to provide normal daily accommodations for people. 
Single-use shelters are always ready for occupants and will not be cluttered 
with furnishings and storage items, which is a concern with multi-use shelters. 
Simplified, single-use shelters may have a lower total cost of construction than 
multi-use shelters. 

The cost of building a single-use shelter is much higher than the additional 
cost of including shelter protection in a multi-use room. Existing maintenance 
plans will usually consider multi-use rooms, but single-use shelters can be 
expected to require an additional annual maintenance cost.

- Multi-use	shelters. The ability to use a shelter for more than one purpose 
often makes a multi-use standalone or internal shelter appealing to a shelter 
owner or operator. Multi-use shelters also allow immediate return on investment 
for owners/operators; the shelter space is used for daily business when the 
shelter is not being used during a hazard event. Hospitals, assisted living 
facilities, and special needs centers would benefit from multi-use internal 
shelters, such as hardened intensive care units or surgical suites. Internal 
multi-use shelters in these types of facilities allow optimization of space 
while providing near-absolute protection with easy access for non-ambulatory 
persons. In new buildings being designed and constructed, recent FEMA-sponsored 
projects have indicated that the construction cost of hardening a small area or 
room in a building is 10 to 25 percent higher than the construction cost for a 
non-hardened version of the same area or room.

- Community	shelters at	neighborhoods and	or public facilities. Community 
shelters are intended to provide protection for the residents of neighborhoods 
and are typically located at schools and other similar institutions; they are 
identified, categorized, and labeled by the American Red Cross (see ARC 4496). 

1.5 Siting

One of the most important elements in designing a shelter is its location or 
siting. In inspecting areas of existing buildings that are used as shelter 
areas, research has found that owners may overlook the safest area of a 
building, while the safety of a hallway or other shelter areas may be 
overestimated. Evaluating shelter areas in an existing building or determining 
the best areas for new ones is invaluable for saving lives when a disaster 
strikes.

The location of a shelter on a building site is an important part of the design 
process for shelters. The shelter location on the site and capacity should 
consider how many occupants work in the building, as well as how many non-
occupants may take refuge in the nearest shelter available. At the site and 
building level, the shelter location analysis should include evaluation of 
potential CBRE effects. 

When deciding to build a shelter, a preliminary evaluation may be performed by a 
design professional or by a potential shelter owner, property owner, emergency 
manager, building maintenance person, or other interested party provided he or 
she has a basic knowledge of building sciences and can understand building 
design plans and specifications. Although	the threat of damage from CBRE events 
may be the predominant focus of the evaluation,	additional	threats may	exist 
from tornado, hurricane, flood, and	seismic events; therefore, the evaluation 
should assess the threat at the site. Prior to the design and construction of a 
shelter, a design professional should perform a more thorough assessment in 
order to confirm or, as necessary, modify the findings of a preliminary 
assessment. 

An entire building or a section of a building may be designated as a potential 
shelter area. To perform an assessment of an existing structure or a new 
structure to be used as a shelter, the building owner or designers may use the 
Building Vulnerability Assessment Checklist included in FEMA 426, Reference 
Manual to Mitigate Potential Terrorist Attacks Against Buildings; FEMA 452, A 
How-To Guide to Mitigate Potential Terrorist Attacks Against Buildings for the 
assessment of CBRE events; and FEMA 433, Using HAZUS-MH for Risk Assessment for 
the assessment of major natural hazards. 

If an existing building is selected for use as a shelter, the Building 
Vulnerability Assessment Checklist will help the user identify major 
vulnerabilities and/or the best shelter areas within the building to place the 
shelter. The checklist consists of questions pertaining to structural, 
nonstructural, and mechanical characteristics of the area being considered. The 
questions are designed to identify structural, nonstructural, and mechanical 
vulnerabilities to CBRE hazards based on typical failure mechanisms. Structural, 
nonstructural, and mechanical deficiencies may be remedied with retrofit 
designs; however, depending on the type and degree of deficiency, the evaluation 
may indicate that the existing structure is unsuitable for use as a shelter 
area. A detailed analysis should consider if a portion of a particular building 
can be used as shelter or whether that portion is structurally independent of 
the rest of the building. It should also determine if the location is easily 
accessible, contains the required square footage, and has good ingress and 
egress elements.

The shelter should be located such that all persons designated to take refuge 
may reach the shelter with minimal travel time. Shelters located at one end of a 
building or one end of a community, office complex, or school may be difficult 
for some users at a site to reach in a timely fashion. Routes to the shelter 
should be easily accessible and well marked. Exit routes from the shelter should 
be in a direction away from the threat. Hazard signs should be located following 
Crime Prevention Through Environmental Design (CPTED) principles of natural 
access control, natural surveillance, and territoriality and illustrated in 
Figure 1-4.

Figure 1-4: Example of shelter marking on building, floor plan, and exterior 
exits to rally points. Illustration of a ground floor plan of a building showing 
primary and secondary egress locations and the stairwell exit.

- Natural access control (controls access). Guides people entering and leaving a 
space through the placement of entrances, exits, fences, landscaping, and 
lighting. Access control can decrease opportunities for terrorist activity by 
denying access to potential targets and creating a perception of risk for would-
be terrorists.

- Natural surveillance (increases visibility). The placement of physical 
features, activities, and people in a way that maximizes visibility. A potential 
criminal is less likely to attempt an act of terrorism if he or she is at risk 
of being observed. At the same time, we are likely to feel safer when we can see 
and be seen.

- Territoriality (promotes a sense of ownership). The use of physical attributes 
that express ownership such as fences, signage, landscaping, lighting, pavement 
designs, etc. Defined property lines and clear distinctions between private and 
public spaces are examples of the application of territoriality. Territoriality 
can be seen in gateways into a community or neighborhood.

Shelters should also be located outside areas known to be flood-prone, including 
areas within the 100-year floodplain. Shelters in flood-prone areas will be 
susceptible to damage from hydrostatic and hydrodynamic forces associated with 
rising flood waters. Damage may also be caused by debris floating in the water. 
Most importantly, flooding of occupied shelters may well result in injuries or 
deaths. Furthermore, shelters located in flood-prone areas, but properly 
elevated above the 100-year flood elevation, could become isolated if access 
routes were flooded. As a result, shelter occupants could be injured and no 
emergency services would be available.

Where possible, the shelter should be located away from large objects and multi-
story buildings. Light towers, antennas, satellite dishes, and roof-mounted 
mechanical equipment may be toppled or become airborne during blast, hurricane, 
tornado, or earthquake events. Multi-story buildings adjacent to a shelter may 
be damaged or may fail structurally due to natural or manmade hazards. When 
these types of objects or structures fail, they may damage the shelter by 
collapsing onto it or impacting it. The impact forces associated with these 
objects are well outside the design parameters of any building code.

There are several possible locations in a building or a house for a shelter. 
Perhaps the most convenient and safest is below ground level, in a basement. If 
the building or house does not have a basement, an in-ground shelter can be 
installed beneath a concrete slab-on-grade foundation or a concrete garage floor 
(typically would be used as a single-use shelter). Basement shelters and in-
ground shelters provide the greatest degree of protection against missiles and 
falling debris.

Another alternative shelter location is an interior room on the first floor of a 
building or house. Closets, bathrooms, and small storage rooms offer the 
advantage of having a function other than providing occasional storm protection. 
Typically, these rooms have only one door and no windows, which make them well-
suited for conversion to a shelter. Bathrooms have the added advantage of a 
water supply and toilet.

Regardless of where in a building or house a shelter is built, the walls and 
ceiling of the shelter must be built so that they will protect the occupants 
from missiles and falling debris, and so that they will remain standing if the 
building or house is severely damaged by extreme winds. If sections of the 
building or house walls are used as shelter walls, those sections must be 
separated from the structure of the building or house. This is true regardless 
of whether interior or exterior walls of the building or house are used as 
shelter walls.

Typical floor plans of possible locations for shelters in a home are highlighted 
in yellow in Figures 1-5 and 1-6. These are not floor plans developed 
specifically for houses with shelters, but they show how shelters can be added 
without changes to the layout of rooms.

Figure 1-5: Examples of internal shelter locations in a residential slab on 
grade foundation
Source: FEMA 320

Figure 1-6: Examples of internal shelter locations in a residential basement
Source: FEMA 320

Figures 1-7 through 1-9 show examples of internal shelter locations in a 
commercial basement, concourse, and underground parking garage; a 
retail/commercial multi-story building using a parking garage, conference rooms, 
data centers, stairwells, and elevator core areas; and a school/church facility, 
respectively.

Figure 1-7: Examples of internal shelter locations in a commercial building

Figure 1-8: Examples of internal shelter locations in a retail/commercial multi-
story building using parking garage, conference rooms, data centers, stairwells, 
and elevator core areas

Figure 1-9: Examples of internal shelter locations in a school/church facility. 
An illustration showing the main building with an airlock (if required) entrance 
leading to a safe room (toxic free area which has a toxic-free envelope around 
it). 

Currently, standalone shelters are relatively rare and most remaining shelters 
are remnants of the Cold War era that were designed for nuclear weapons 
protection as fallout shelters. These shelters were called dedicated 
shelters to make a clear differentiation from dual use shelters (normal 
facilities in the community that had enhanced radiation protection). Dedicated 
shelters were built with very high levels of protection and did not have peace 
time functional compromises. Siting of standalone shelters for nuclear 
protection has typically been underground, as tunnels, caves, or buried 
structures. The mass of the geological materials absorbed the blast energy and 
provided radiation shielding.

Many of the siting and design principles developed by the Office of Civil 
Defense in FEMA TR-29, Architect & Engineer Activities in Shelter Development; 
FEMA RR-7, Civil Defense Shelters A State of the Art Assessment 1986; and FEMA 
TR-87, Standards for Fallout Shelters are still applicable.

For a standalone shelter, many sites will be constrained or site limited for 
underground, and an aboveground structure may be the only feasible alternative. 
For these sites, the siting considerations include:

- Outside the floodplain

- Separation distance between buildings and structures to prevent progressive 
collapse or impact from collapsing elements

- Separation from major transportation features (road, rail)

- Access to redundant power and communications capabilities

1.6 Occupancy Duration, Toxic-free Area (TFA) Floor Space, and Ventilation 
Requirements

Occupancy duration (also known as button-up time) is the length of time that 
people will be in the shelter with the doors closed and in the protected 
environment. This period of time is determined by the building owner or local 
authorities and can range from several hours to several days. For off-site 
industrial accidents, the occupancy duration is usually less than 24 hours; 
occupancy durations longer than 24 hours are generally restricted to wartime. 
Occupancy duration stops when the doors to the shelter are opened. It influences 
the floor area requirements and the amount of consumable and waste storage. 
Generally, occupancy duration will not significantly affect the performance of 
the collective protection system.

[Begin text box]
CBR Collective Protection Shelter Basics
- Occupancy Duration
- Toxic-free Area (TFA) Floor Space
- Ventilation Requirements
[End text box]

a. Less Than 24 Hours. An occupancy duration of less than 24 hours does not 
require sleeping areas. The occupant load will generally be a net 1.86 m2/person 
(20 square feet/person), depending upon the classification of occupancy. The 
classification of occupancy, as stated in NFPA 101, may require a higher or 
lower occupant loading depending upon the building classification. The occupant 
loading will be coordinated with the authority having jurisdiction.

b. More Than 24 Hours. An occupancy duration greater than 24 hours requires 
sleeping areas. The minimum floor area, with the use of single size beds, is 
approximately 5.6 m2/person (60 square feet/person). With the use of bunked 
beds, the minimum floor area is approximately 2.8 m2/person (30 square 
feet/person).

The total required TFA floor space is determined from the occupancy duration, 
the number of people sheltered, and the required floor area per person. 
Generally, large open areas such as common areas, multi-purpose areas, 
gymnasiums, etc., provide the most efficient floor area for protecting a large 
number of personnel. The TFA envelope should include bathroom facilities and, 
if possible, kitchen facilities.

Although the planned response to CBR events may be to temporarily deactivate the 
ventilation systems, both single- and multi-use shelters must include 
ventilation systems capable of providing the minimum number of air changes 
required by the building code for the shelters occupancy classification. This 
will provide a flushing capability once the CBR hazard has passed and facilitate 
use of the shelter for non-CBR events. For single-use shelters, 15 cubic feet 
per person per minute is the minimum air exchange recommended; this 
recommendation is based on guidance outlined in the International Mechanical 
Code (IMC). For multi-use shelters, the design of mechanical ventilation systems 
is recommended to accommodate the air exchange requirements for the occupancy 
classification of the normal use of the shelter area. Although the ventilation 
system may be overwhelmed in a rare event when the area is used as a shelter, 
air exchange will still take place. The designer should still confirm with the 
local building official that the ventilation system may be designed for the 
normal-use occupancy. In the event the community where the shelter is to be 
located has not adopted a model building and/or mechanical code, the 
requirements of the most recent edition of the International Building Code (IBC) 
are recommended.

1.7 Human Factors Criteria

Human factors criteria for the natural and manmade hazard shelters build on 
existing guidance provided in this chapter and in FEMA 320 and 361. Although 
existing documents do not address all the human factors involved in the design 
of CBRE shelters, they provide the basis for the criteria summarized in this 
chapter. These criteria are detailed in the following sections.

1.7.1 Square Footage/Occupancy Requirements 

The duration of occupancy of a shelter will vary, depending on the intended 
event for which the shelter has been designed. Occupancy duration is an 
important factor that influences many aspects of the design process. 

The recommended minimums are 5 square feet per person for tornado shelters and 
10 square feet per person for hurricane shelters. The shelter designer should be 
aware of the occupancy requirements of the building code governing the 
construction of the shelter. The occupancy loads in the building codes have 
historically been developed for life safety considerations. Most building codes 
will require the maximum occupancy of the shelter area to be clearly posted. 
Multi-use occupancy classifications are provided in the IBC; NFPA 101, Life 
Safety Code; NFPA 5000, Building Construction and Safety Code; and state and 
local building codes. Conflicts may arise between the code-specified occupancy 
classifications for normal use and the occupancy needed for sheltering. For 
example, according to the IBC and NFPA 101 and 5000, the occupancy 
classification for educational use is 20 square feet per person; however, the 
recommendation for a tornado shelter is 5 square feet per person. Without proper 
signage and posted occupancy requirements, using an area in a school as a 
shelter can create a potential conflict regarding the allowed number of persons 
in the shelter. If both the normal maximum occupancy and the shelter maximum 
occupancy are posted, and the shelter occupancy is not based on a minimum less 
than the recommended 5 square feet per person, the shelter design should be 
acceptable to the building official. The IBC, NFPA 101 and 5000, and the model 
building codes all have provisions that allow occupancies as concentrated as 5 
square feet per person. The American Society of Heating, Refrigeration, and Air-
Conditioning Engineers (ASHRAE) recommends that a minimum head room of 6.5 feet 
and a minimum of 65 cubic feet of net volume be provided per shelter occupant. 
Net volume shall be determined using the net area calculated for the space.

ASHRAE Ventilation Standard 62-1981, Ventilation for Smoking-Permitted Areas 
defines minimum outdoor air supply rates for various types of occupancy. These 
rates have been arrived at through a consensus of experts working in the field. 
A minimum rate of 5 cfm per person for sedentary activity and normal diet holds 
the carbon dioxide (CO2) level in a space at 0.25 percent under steady state 
conditions. Although normal healthy people tolerate 0.5 percent CO2 without 
undesirable symptoms and nuclear submarines sometimes operate with 1 percent CO2 
in the atmosphere, a level of 0.25 percent provides a safety factor for 
increased activity, unusual occupancy load, or reduced ventilation. The ASHRAE 
Handbook 1982 Applications Environmental Control for Survival states that carbon 
dioxide concentration should not exceed 3 percent by volume and preferably 
should be maintained below 0.5 percent. For a sedentary man, 3 cfm per person of 
fresh air would maintain a CO2 concentration of 0.5 percent.

1.7.1.1 Tornado or Short-term Shelter Square Footage Recommendations. Historical 
data indicate that tornado shelters will typically have a maximum occupancy time 
of 2 hours. Because the occupancy time is so short, many items that are needed 
for the comfort of occupants for longer durations (in hurricane shelters) are 
not recommended for a tornado shelter. FEMA 361, Section 8.2 recommends a 
minimum of 5 square feet per person for tornado shelters. However, other 
circumstances and human factors may require the shelter to accommodate persons 
who require more than 5 square feet. Square footage recommendations for persons 
with special needs are presented below; these recommendations are the same as 
those provided in the FEMA 1999 National Performance Criteria for Tornado 
Shelters: 
- 5 square feet per person adults standing 
- 6 square feet per person adults seated 
- 5 square feet per person children (under the age of 10) 
- 10 square feet per person wheelchair users 
- 30 square feet per person bedridden persons 

1.7.1.2 Hurricane	or Long-term Shelter Square Footage Recommendations. 
Historical data indicate that hurricane shelters will typically have a maximum 
occupancy time of 36 hours. For this reason, the occupants of a hurricane 
shelter need more space and comforts than the occupants of a tornado shelter. 
FEMA 361, Section 8.2 recommends a minimum of 10 square feet per person for 
hurricane shelters (for a hurricane event only; an event expected to last less 
than 36 hours). The American Red Cross 4496 publication recommends the following 
minimum floor areas (Note: the ARC square footage criteria are based on long-
term use of the shelter [i.e., use of the shelter both as a refuge area during 
the event and as a recovery center after the event]): 

- 20 square feet per person for a short-term stay (i.e., a few days) 
- 40 square feet per person for a long-term stay (i.e., days to weeks) 

Again, the designer should be aware that there can be conflicts between the 
occupancy rating for the intended normal use of the shelter and the occupancy 
required for sheltering. This occupancy conflict can directly affect exit 
(egress) requirements for the shelter. 

1.7.2	Distance/Travel Time and Accessibility 

The shelter designer should consider the time required for all occupants of a 
building or facility to reach the shelter. The National Weather Service (NWS) 
has made great strides in predicting tornadoes and hurricanes and providing 
warnings that allow time to seek shelter; it has now expanded the service to 
include all hazards. As part of the NIMS, for tornadoes, the time span is often 
short between the NWS warning and the onset of the tornado. Figure 1-10 shows a 
sample NWS current watches, warnings, statements, and advisories summary. This 
manual recommends that a tornado shelter be designed and located in such a way 
that the following access criteria are met: all potential users of the shelter 
should be able to reach it within 5 minutes, and the shelter doors should be 
secured within 10 minutes. For hurricane shelters, these restrictions do not 
apply, because warnings are issued much earlier, allowing more time for 
preparation. A CBRE event may have warning such as the Irish Republican Army 
gave to London police and residents, or no warning as happened with the events 
of 9/11, and anthrax and sarin releases in October 2001 and the Tokyo subway, 
respectively.

Figure 1-10: National Weather Service forecast and warnings. An illustration 
showing the current watches, warnings, statements, and advisories.
Source: NWS

Travel time may be especially important when shelter users have disabilities 
that impair their mobility. Those with special needs may require assistance from 
others to reach the shelter; wheelchair users may require a particular route 
that accommodates the wheelchair. The designer must consider these factors in 
order to provide the shortest possible access time and most accessible route for 
all potential shelter occupants. 

Access is an important element of shelter design. If obstructions exist along 
the travel route, or if the shelter is cluttered with non-essential equipment 
and storage items, access to the shelter will be impeded. It is essential that 
the path remain unencumbered to allow orderly access to the shelter. Hindering 
access in any way can lead to chaos and panic. For example, at a community 
shelter built to serve a residential neighborhood, parking at the shelter site 
may complicate access to the shelter; at a non-residential shelter, such as at a 
manufacturing plant, mechanical equipment can impede access. 

Unstable or poorly secured building elements could potentially block access if a 
collapse occurs that creates debris piles along the access route or at 
entrances. A likely scenario is an overhead canopy or large overhang that lacks 
the capacity to withstand blast effects collapses over the entranceway. The 
inclusion of these elements should be seriously considered when designing access 
points in shelters.

1.7.3	Americans with Disabilities Act (ADA)

The needs of persons with disabilities requiring shelter space should be 
considered. The appropriate access for persons with disabilities must be 
provided in accordance with all Federal, state, and local ADA requirements and 
ordinances. If the minimum requirements dictate only one ADA-compliant access 
point for the shelter, the design professional should consider providing a 
second ADA-compliant access point for use in the event that the primary access 
point is blocked or inoperable. Additional guidance for compliance with the ADA 
can be found in many privately produced publications. 

The design professional can ensure that the operations plan developed for the 
shelter adheres to requirements of the ADA by assisting the owner/operator of 
the shelter in the development of the plan. All shelters should be managed with 
an operations and maintenance plan. Developing a sound operations plan is 
extremely important if compliance with ADA at the shelter site requires the use 
of lifts, elevators, ramps, or other considerations for shelters that are not 
directly accessible to non-ambulatory persons.

1.7.4 Special Needs

The use of the shelter also needs to be considered in the design. Occupancy 
classifications, life safety code, and ADA requirements may dictate the design 
of such elements as door opening sizes and number of doors, but use of the 
shelter by hospitals, nursing homes, assisted living facilities, and other 
special needs groups may affect access requirements to the shelter. For example, 
basic requirements are outlined in the IBC and NFPA 101 and 5000 regarding the 
provision of uninterruptible power supplies for life support equipment (e.g., 
oxygen) for patients in hospitals and other health care facilities. NFPA 99, 
Standard for Healthcare Facilities, specifies details on subjects such as the 
type, class, and duration of power supplies necessary for critical life support 
equipment. In addition, it also details the design, arrangement, and 
configuration of medical gas piping systems, alarms, and networks. 

In addition, strict requirements concerning issues such as egress, emergency 
lighting, and detection-alarm-communication systems are presented in Chapter 10 
of the IBC and in NFPA 101, 2006 Edition, Chapters 18 and 19, for health care 
occupancies. The egress requirements for travel distances, door widths, and 
locking devices on doors for health care occupancies are more restrictive than 
those for an assembly occupancy classification in non-health care facilities 
based on the model building codes for non-health care facilities. Additional 
requirements also exist for health care facilities that address automatic fire 
doors, maximum allowable room sizes, and maximum allowable distances to egress 
points. The combination of all these requirements could lead to the construction 
of multiple small shelters in a health care facility rather than one large 
shelter. 

1.8 Other Design Considerations

Emergency lighting and power, as well as a backup power source, need to be 
included in the design of multi-use shelters. Route marking and wayfinding, and 
signage also should be included.

1.8.1 Lighting 

For the regular (i.e., non-shelter) use of multi-use shelters, lighting, 
including emergency lighting for assembly occupancies, is required by all model 
building codes. Emergency lighting is recommended for community shelters. A 
backup power source for lighting is essential during a disaster because the main 
power source is often disrupted. A battery-powered system is recommended as the 
backup source because it can be located, and fully protected, within the 
shelter. Flashlights stored in cabinets are useful as secondary lighting 
provisions, but should not be used as the primary backup lighting system. 
A reliable lighting system will help calm shelter occupants during a disaster. 
Failing to provide proper illumination in a shelter may make it difficult for 
shelter owners/operators to minimize the agitation and stress of the shelter 
occupants during the event. If the backup power supply for the lighting system 
is not contained within the shelter, it should be protected with a structure 
designed to the same criteria as the shelter itself. Natural lighting provided 
by windows and doors is often a local design requirement, but is not required by 
the IBC for assembly occupancies. The 2003 edition of the IBC and the 2006 
edition of NFPA 5000 has additional guidance on egress, lighting, and markings. 

1.8.2 Emergency Power 

Shelters will have different emergency (backup) power needs based upon the 
length of time that people will stay in the shelters (i.e., shorter duration for 
tornadoes and longer duration for hurricanes). In addition to the essential 
requirements that must be provided in the design of the shelter, comfort and 
convenience should be addressed. 

For tornado shelters, the most critical use of emergency power is for lighting. 
Emergency power may also be required in order to meet the ventilation 
requirements described in Chapter 3 and Section 1.7.1. The user of the shelter 
should set this requirement for special needs facilities, but most tornado 
shelters would not require additional emergency power. 

For hurricane shelters, emergency power may be required for both lighting and 
ventilation. This is particularly important for shelters in hospitals and other 
special needs facilities. Therefore, a backup generator is recommended. Any 
generator relied on for emergency power should be protected with an enclosure 
designed to the same criteria as the shelter.

As illustrated in the previous sections, the manmade hazards shelter design 
criteria require an adjustment to the traditional design process for natural 
hazard shelters. The shelter location, operation, and life-cycle costs are now 
significantly coupled to the community, first responders, and government plans 
and procedures for mass casualty response and recovery; Federal and local laws 
for criminal investigation; and the unique site and building design parameters 
and level of protection that is desired.

1.8.3 Route Marking and Wayfinding 

Route marking or wayfinding in an emergency situation such as total darkness has 
historically relied on fire exit lighting. A new technology that is being 
adopted by many cities is photoluminescent exit path marking. These 
photoluminescent self-adhesive signs and tapes are very visible during the day 
and will glow for up to 8 hours after the light source is removed. These signs 
have durable, permanent, and renewable fluorescence. Figure 1-11 shows sample 
signs.

Figure 1-11: Photoluminescent signs, stair treads, and route markings

[Begin text box]
Reference Standard 6-1

Photoluminescent exit path markings as required by Local Law 26 of 2004, New 
York city Building Code  27-383(b)

This standard is intended to provide minimum requirements for photoluminescent 
exit path markings that will aid in evacuation from buildings in the event of 
failure of both the power and back-up power to the lighting and illuminated exit 
signs. Photoluminescent material is charged by exposure to light and will emit 
luminance after the activating light source is unavailable. The markings covered 
by this standard are not designed to provide enough light to illuminate a dark 
egress path, but rather will provide luminescent signs and outlines of the 
egress path, stairs, handrails, and obstacles, so that occupants can discern 
these egress path elements in dark conditions. The markings are generally 
required to be located at a low location in case of smoke and to be readily 
seen, such as in a crowd situation. They are in addition to, and not as a 
substitute for, any other signage required under the Building Code, such as 
electrically illuminated exit signs with electrical back-up power required under 
 27-383(a).
[End text box]

1.8.4	Signage

The signs should be illuminated, luminescent, and obvious. Key elements of 
signage include the following.

1.8.4.1 Community	and Parking	Signage. It is very important that shelter 
occupants can reach the shelter quickly and without chaos. Parking is often a 
problem at community shelters; therefore, a Community Shelter Operations Plan 
should instruct occupants to proceed to a shelter on foot if time permits. Main 
pathways should be determined and laid out for the community. Pathways should be 
marked to direct users to the shelter. Finally, the exterior of the shelter 
should have a sign that clearly identifies the building as a shelter. 

1.8.4.2 Signage at Schools and Places of Work. Signage for shelters at schools 
and places of work should be clearly posted and should direct occupants through 
the building or from building to building. If the shelter is in a government-
funded or public-funded facility, a placard should be placed on the outside of 
the building designating it an emergency shelter (see Figure 1-12). It is 
recommended that signage be posted on the outside of all other types of shelters 
as well. It is important to note, however, that once a public building has been 
identified as a shelter, people who live or work in the area around the shelter 
will expect the shelter to be open during an event. Shelter owners should be 
aware of this and make it clear that the times when a shelter will be open may 
be limited. For example, a shelter in an elementary school or commercial 
building may not be accessible at night.

Figure 1-12: Shelter signage. A sample of a Multi-Hazards Shelter sign showing 
tornado, toxic gas, and biohazard. 

1.9 Evacuation considerations
When designing a shelter, evacuation is one of the most important aspects to 
save lives. During the attack of the World Trade Center, good and well-marked 
egress was critical for thousands of people to evacuate the buildings. The same 
concept is applicable to shelters. Good ingress and egress, along with 
robustness and redundancy of the structural system, is critical for a sound 
design. 

The matter of high-rise evacuation has become vital since September 11, 2001, as 
a result of the fatalities of almost 3,000 building occupants and emergency 
personnel. Life safety is provided to building occupants by either giving them 
the opportunity to evacuate to a safer place or be protected in place. 

[Begin text box]
Every building should have an emergency evacuation and shelter-in-place plan 
that is coordinated with the local community emergency manager. Building 
stakeholders and tenants should develop the plan with the objective to save 
lives and property, and to recover and restore the business should an event 
occur. The NFPA 1600 Standard on Disaster/Emergency Management and Business 
Continuity Programs publication provides a framework and recommendations for 
developing a plan. The building owner, property manager, and tenants should work 
with the local community to develop an evacuation versus shelter-in-place 
options matrix as shown in Table 1-6. 
[End text box]

The National Institute of Standards and Technology (NIST) Final Report of the 
National Construction Safety Team on the Collapses of the World Trade Center 
Towers conducted analysis of the life safety systems and emergency response to 
validate and expand the state of the practice for high-rise buildings. The NIST 
study was focused on the collapse mechanisms and life safety systems 
performance. 

As a result of the collapse of the World Trade Center towers, NIST identified 
three major scenarios that are not considered adequately in current design 
practice:
- Frequent but low severity events (for design of sprinkler system)
- Moderate but less frequent events (for design of compartmentation)
- A maximum credible fire (for design of passive fire protection on the 
structure)

[Begin table]
Table 1-6: Evacuation Versus Shelter-in-place Options Matrix 

Attack Agent: Chemical  Exterior Release
Timeframe and Protection Objective: Immediate - shelter in safe room, minimize 
duration and concentration exposure
Occupant/Personnel Action: Use portable air filtration, wait for first responder 
extraction
 
Attack Agent: Chemical  Interior Release
Timeframe and Protection Objective: Immediate - don PPE and evacuate, minimize 
duration and concentration exposure
Occupant/Personnel Action: Move perpendicular to plume direction, seek 
decontamination and medical treatment
 
Attack Agent: Biological  Exterior Release
Timeframe and Protection Objective: Immediate - shelter in safe room, do not 
touch agents, use time to advantage to identify safe evacuation route
Occupant/Personnel Action: Use portable air filtration, wait for first responder 
extraction, seek decontamination and medical treatment
 
Attack Agent: Biological  Interior Release
Timeframe and Protection Objective: Immediate - don PPE and evacuate, minimize 
duration and concentration exposure
Occupant/Personnel Action: Seek decontamination and medical treatment
 
Attack Agent: Radiological/Nuclear  Exterior Release
Timeframe and Protection Objective: Immediate - shelter in safe room, minimize 
duration and concentration exposure
Occupant/Personnel Action: Use portable air filtration, wait for first responder 
extraction
 
Attack Agent: Radiological/Nuclear  Interior Release
Timeframe and Protection Objective: Immediate - don PPE and evacuate, minimize 
duration and concentration exposure
Occupant/Personnel Action: Seek decontamination and medical treatment
 
Attack Agent: Explosive Blast - Exterior
Timeframe and Protection Objective: Immediate - shelter in safe room
Occupant/Personnel Action: Use portable air filtration, wait for first responder 
extraction
 
Attack Agent: Explosive Blast - Interior 
Timeframe and Protection Objective: Immediate - don PPE and evacuate
Occupant/Personnel Action: Seek medical treatment
[End table]

Three methods are followed for the evacuation of buildings. One method consists 
of evacuating all occupants simultaneously. Alternatively, occupants may be 
evacuated in phases, where the floor levels closest to the event are evacuated 
first and then other floor levels are evacuated on an as needed basis. Phased 
evacuation is instituted to permit people on the floor levels closest to the 
threatening hazard to enter the stairway unobstructed by queues formed by people 
from all other floors also being in the stairway. Those who are below the 
emergency usually are encouraged to stay in place until the endangered people 
from above are already below this floor level.

The concept of occupant relocation to other floors is usually the best course of 
action for many types of building emergencies. This method normally involves 
movement of occupants, from the fire floor, the floor above, and floor below to 
a lower level until the danger passes.

Evacuation involves providing people with the means to exit the building. The 
egress system involves the following considerations:

Capacity. A sufficient number of exits of adequate width to accommodate the 
building population need to be provided to allow occupants to evacuate safely.

Access. Occupants need to be able to access an exit from wherever the fire is, 
and in sufficient time prior to the onset of untenable conditions. Alternative 
exits should be remotely located so that all exits are not simultaneously 
blocked by a single incident.

Exit Design. Exits need to be separated from all other portions of the building 
in order to provide a protected way of travel to the exit discharge. This 
involves designing to preclude fire and smoke from entering the exit and will 
usually involve structural stability.

In general, the means of egress system is designed so that occupants travel 
from the office space along access paths such as corridors or aisles until they 
reach the exit or a safer place. An exit is commonly defined as a protected path 
of travel to the exit discharge (NFPA 101, 2006). The stairways in a high-rise 
building commonly meet the definition of an exit. In general, the exit is 
intended to provide a continuous, unobstructed path to the exterior or to 
another area that is considered safe. Most codes require that exits discharge 
directly to the outside. Some codes, such as NFPA 101, permit up to half of the 
exits to discharge within the building, given that certain provisions are met.

There is no universally accepted standard on emergency evacuation. Design 
considerations for high-rise buildings relative to these two options involve 
several aspects, including design of means of egress, the structure, and active 
fire protection systems (e.g., detection and alarm, suppression, and smoke 
management). Many local jurisdictions, through their fire department public 
education programs, have developed comprehensive and successful evacuation 
planning models but, unless they are locally adopted, there is no legal mandate 
to exercise the plans. Seattle, Phoenix, Houston, and Portland, Oregon, are 
among the cities that have developed comprehensive programs.

The NIST life safety, egress, and emergency response findings provide valuable 
lessons learned for future shelter evacuation design. Currently, building fire 
protection is based on a four-level hierarchical strategy comprising alarm and 
detection, suppression (sprinklers and firefighting), compartmentation, and 
passive protection of the structure. 

- Manual stations and detectors are typically used to activate fire alarms and 
notify building occupants and emergency services.

- Sprinklers are designed to control small and medium fires and to prevent fire 
spread beyond the typical water supply design area of about 1,500 square feet.

- Compartmentation mitigates the horizontal spread of more severe but less 
frequent fires and typically requires fire-rated partitions for areas of about 
12,000 square feet. Active firefighting measures also cover up to about 5,000 
square feet to 7,500 square feet.

- Passive protection of the structure seeks to ensure that a maximum credible 
fire scenario, with sprinklers compromised or overwhelmed and no active 
firefighting, results in burnout, not overall building collapse. The intent of 
building codes is also for the building to withstand local structural collapse 
until occupants can escape and the fire service can complete search and rescue 
operations.

NIST recommends that building evacuation should be improved to include system 
designs that facilitate safe and rapid egress, methods for ensuring clear and 
timely emergency communications to occupants, better occupant preparedness for 
evacuation during emergencies, and incorporation of appropriate egress 
technologies. When designing good evacuation systems and routes of ingress and 
egress, designers should take into account the following considerations:  

- As stated above, improved building evacuation, including system designs that 
facilitate safe and rapid egress, methods for ensuring clear and timely 
emergency communications to occupants, better occupant preparedness for 
evacuation during emergencies, and incorporation of appropriate egress 
technologies. Primary and secondary evacuation routes and exits should be 
designated and clearly marked and well lit. Signs should be posted.

- Improved emergency response, including better access to the buildings and 
better operations, emergency communications, and command and control in large-
scale emergencies.

- Emergency lighting should be installed in case a power outage occurs during an 
evacuation.

- Evacuation routes and emergency exits should be:
 - wide enough to accommodate the number of evacuating personnel.
 - clear and unobstructed at all times.
 - unlikely to expose evacuating personnel to additional hazards.
- Evacuation routes should be evaluated by a professional.

[Begin recommendations]
Recommendation 16. NIST recommends that public agencies, non-profit 
organizations concerned with building and fire safety, and building owners and 
managers should develop and carry out public education campaigns, jointly and on 
a nationwide scale, to improve building occupants preparedness for evacuation 
in case of building emergencies.

Recommendation 17. NIST recommends that tall buildings should be designed to 
accommodate timely full building evacuation of occupants due to building-
specific or large-scale emergencies such as widespread power outages, major 
earthquakes, tornadoes, hurricanes without sufficient advanced warning, fires, 
accidental explosions, and terrorist attacks. Building size, population, 
function, and iconic status should be taken into account in designing the egress 
system. Stairwell and exit capacity should be adequate to accommodate 
counterflow due to emergency access by responders.

Recommendation 18. NIST recommends that egress systems should be designed: (1) 
to maximize remoteness of egress components (i.e., stairs, elevators, exits) 
without negatively impacting the average travel distance; (2) to maintain their 
functional integrity and survivability under foreseeable building-specific or 
large-scale emergencies; and (3) with consistent layouts, standard signage, and 
guidance so that systems become intuitive and obvious to building occupants 
during evacuations.

Recommendation 19. NIST recommends that building owners, managers, and emergency 
responders develop a joint plan and take steps to ensure that accurate emergency 
information is communicated in a timely manner to enhance the situational 
awareness of building occupants and emergency responders affected by an event. 
This should be accomplished through better coordination of information among 
different emergency responder groups, efficient sharing of that information 
among building occupants and emergency responders, more robust design of 
emergency public address systems, improved emergency responder communication 
systems, and use of the Emergency Broadcast System (now known as the Integrated 
Public Alert and Warning System) and Community Emergency Alert Networks.

Recommendation 21. NIST recommends the installation of fire-protected and 
structurally hardened elevators to improve emergency response activities in tall 
buildings by providing timely emergency access to responders and allowing 
evacuation of mobility-impaired building occupants. Such elevators should be 
installed for exclusive use by emergency responders during emergencies. In tall 
buildings, consideration also should be given to installing such elevators for 
use by all occupants.
[End recommendations]

[Begin text box]
The 2006 editions of NFPA 101, Life Safety Code and NFPA 5000, Building 
Construction and Safety Code addressed the issue of counter-flow between first 
responders and descending occupants. The new provisions mandate a minimum stair 
width of 56 inches (1,420 mm) when a stair is designed to handle an aggregate or 
accumulated of 2,000 or more occupants. Previous criteria required 44 inches 
(1,120 mm) minimum.
[End text box]

It is also important to designate assembly areas and a means of obtaining an 
accurate account of personnel after a site evacuation. Designate areas where 
personnel should gather after evacuating (see Section 1.10). A head count should 
be taken after the evacuation. The names and last known locations of personnel 
not accounted for should be determined and given to the Emergency Operations 
Coordinator (EOC). (Confusion in the assembly areas can lead to unnecessary and 
dangerous search and rescue operations.) A method for accounting for non-
employees (e.g., suppliers and customers) should also be established.
In addition, procedures should be established for further evacuation in case the 
incident expands. This may consist of sending employees home by normal means or 
providing them with transportation to an off-site location.

1.10 Key Operations Zones

Key operations zones refer to the shelter site surrounding areas and entry and 
exit control points that need to be taken into consideration when designing a 
shelter.   

For catastrophic incidents depicted in the planning scenarios related to the 
National Response Plan  catastrophic Incident (NRP-CIS), decontamination 
involves several related and sequential activities. Chief among these are (1) 
immediate (or gross) decontamination of persons exposed to toxic/hazardous 
substances; (2) continual decontamination of first responders so that they can 
perform their essential functions; (3) decontamination of animals in service to 
first responders; (4) continual decontamination of response equipment and 
vehicles; (5) secondary, or definitive, decontamination of victims at medical 
treatment facilities to enable medical treatment and protect the facility 
environment; (6) decontamination of facilities (public infrastructure, business 
and residential structures); and (7) environmental (outdoor) decontamination 
supporting recovery and remediation.

1.10.1 Containment Zones

There are three zones of containment after an event:

- Hot Zone (the area where the agent or contamination is in high concentration 
and high exposure, typically an ellipse or cone extending downwind from the 
release)

- Warm Zone (the area where the agent or contamination is in low concentration 
or minimal exposure, typically a half circle in the above wind direction)

- Cold Zone (those areas outside of the Hot and Warm zones that have not been 
exposed to the agent or contamination)

The three zones and staging areas are shown in Figure 1-13.

Figure 1-13: Operations Zones, casualty collection Point (CCP), and safe refuge 
area (SRA). An illustration showing the hot zone and warm zone and the casualty 
collection points which are: 1. Litter decontamination, non-ambulatory delayed 
treatment; 2. Litter decontamination, immediate treatment; 3. Ambulatory, 
decontamination minimal, treatment ambulatory, delayed treatment. Mass 
decontamination occurs in the warm zone. Safe refuge area in the warm zone used 
to assemble individuals who are witnesses to the incident and separation of 
contaminated from non-contaminated persons .

Shelter occupants should not leave the shelter until rescue personnel arrive to 
escort occupants to the Cold Zone. The building occupants must go through 
several staging areas to ensure that any CBR contamination is not spread across 
a larger geographical area. There are two processes currently used to evacuate 
an area; the Ladder Pipe Decontamination System (LDS, see Figure 1-14) and the 
Emergency Decontamination Corridor System (EDCS, see Figure 1-15).

[Begin Figure]
Figure 1-14: NRP-CIS Ladder Pipe decontamination system (LDS)
Source: NRP-CIS

Ladder Pipe Decontamination System (LDS)
Advantages
- Rapid setup time
- Provides large capacity high volume low pressure shower
- Rapid hands-free mass decontamination
Disadvantages
- No privacy
- Increased chance of hypothermia from exposure to elements
Composed of:
- Ladder pipe/truck
- 2 engines
- Hand-held hose lines
Setup:
- Engines placed approximately 20 feet apart
- 2 1/2-inch fog nozzles set at wide fog pattern attached to pump discharges
- Truck with fog nozzle placed on ladder pipe to provide downward fog pattern

Firefighters (FFs) can be positioned at either or both ends of the shower area 
to apply additional decontamination wash
[End Figure]

[Begin Figure]
Figure 1-15: NRP-CIS emergency decontamination corridor system (EDCS)
Source: NRP-CIS

Emergency Decontamination Corridor System (EDCS)
Advantages
- Privacy for victims
- Separate male/female corridors
- Shower area can be heated using portable heaters
Disadvantages
- Slower setup time than LDS
- Casualty processing slower
- Requires more manpower to set up
Composed of:
- 2 engines
- Salvage covers
Setup:
- 2 engines placed approximately 20 feet apart
- 3 ladders placed and secured to top of engines
- 4th ladder centered atop the other three ladders and secured
- 2 nozzles secured to the 4th ladder hanging down into the shower area
- Salvage covers draped over ladders to create corridors
[End Figure]

1.10.2 Staging Areas and Designated Entry and Exit Access Control Points

To control the potential spread of a CBRE agent and ensure the safety of the 
victims and first responders, the Incident Commander (IC) will establish several 
staging areas and designated entry and exit access control points for the three 
zones.

- Patient Staging Area (PSA). The PSA is located in the Cold Zone and is the 
transfer point for victims that have been stabilized for transport to higher 
care medical facilities or for fatalities to be transported to morgue facilities 
(see Figures 1-16 and 1-17). The PSA area must be large enough to accommodate 
helicopter operations and a large number of ambulances.

Figure 1-16: Patient staging area and remains recovery. Photos of various 
patient staging areas.
Source: Arlington County After-Action Report

Figure 1-17: Example of Pentagon staging and recovery operations
Source: Arlington County After-Action Report

- Contamination Control	Area (CCA). The CCA (see Figure 1-18) is located on the 
boundary of the Cold Zone and Warm Zone and used by the rescue and 
decontamination personnel to enter and exit the Warm Zone. There are several 
processing stations, a resupply and refurbishment area, and a contaminated waste 
storage area. Mass casualty decontamination occurs in the Warm Zone. 

[Begin Figure}
Figure 1-18: Contamination control area (CCA). An illustration showing the Warm 
Zone which contains Station 1, arrival and initial decontamination, and Station 
2, PPE removal. The Cold Zone, contains Station 3, systems PPE check and Station 
4, arrival and setup

- Safe Refuge Area (SRA). The SRA is located in the Warm Zone and used to 
assemble survivors and witnesses that are not injured and will require minimal 
medical attention and decontamination. Law enforcement and FBI agents can 
conduct interviews and gather evidence at the SRA. 

Evidence collection can occur in any of the three zones as shown in Figure 1-19.

Figure 1-19: Site and evidence collection on the site. Examples of site photos.
Source: Arlington County After-Action Report

Designated entry/exit access control points will be between each of the zones. 
The entry/exit access control point between the Hot and Warm Zones is used by 
the first responders in PPE to enter/exit the Hot Zone and extract victims and 
casualties (both contaminated and uncontaminated) to the Warm Zone. The patient 
entry/exit access control point between the Warm and Cold Zones is used as a 
one-way exit out to move decontaminated uninjured personnel and medically 
stabilized casualties. The first responders entry/exit between the Cold and Warm 
Zones is used by the first responders, rapid visualization and structural 
evaluation team, and debris operations personnel to enter and exit the site, and 
includes equipment shown in Figure 1-20.

Figure 1-20: Rescue team coordination prior to entering a site. Examples of site 
photos.
Source: Arlington County After-Action Report 
 
Between the Hot Zone entry access control point and the patient exit control 
point, there will be a casualty collection point. The CCP (Figure 1-13) is 
located in the Warm Zone and will typically have three processing stations:

- Station 1  Litter decontamination and non-ambulatory delayed treatment 
patients

- Station 2  Litter decontamination and immediate treatment patients

- Station 3  Ambulatory decontamination, minimal treatment patients, and 
ambulatory delayed treatment patients