THIS
DOCUMENT IDENTIFIES ACTIONS that a building owner or manager can
implement without undue delay to enhance occupant protection from
an airborne chemical, biological, or radiological (CBR) attack.
The intended audience includes building owners, managers, and maintenance
personnel of public, private, and governmental buildings, including
offices, laboratories, hospitals, retail facilities, schools, transportation
terminals, and public venues (for example, sports arenas, malls,
coliseums). This document is not intended to address single family
or low-occupancy residential housing (less than five family units).
Higher risk facilities such as industrial facilities, military facilities,
subway systems, and law enforcement facilities require special considerations
that are beyond the scope of this guide.
The
likelihood of a specific building being targeted for terrorist activity
is generally difficult to predict. As such, there is no specific
formula that will determine a certain building’s level of risk.
Building owners must make their own decisions about how to reduce
their building’s risk to a CBR attack. These decisions may
be aided by a comprehensive building security assessment. Many government
and private organizations have identified resources that provide
insight into building security assessments. The reference list at
the end of this document will help the reader obtain this information.
No
building can be fully protected from a determined individual who
is intent on releasing a CBR agent. The recommendations in this
guide will not preclude injuries or fatalities in the event of a
CBR release. . However, facility owners and managers can transform
their buildings into less attractive targets by increasing the difficulty
of introducing a CBR agent, by increasing the ability to detect
terrorists before they carry out an intended release, and by incorporating
plans and procedures to mitigate the effects of a CBR release. Some
of the references listed in the back of this document can provide
information on how to recognize if a CBR release has occurred. These
recommendations focus on airborne releases of CBR agents* in quantities
capable of being easily transported by a few individuals. Protection
from other types of attacks such as explosions, building collapses,
and water supply contamination require much different measures and
are not addressed in this document.
The
recommendations set forth in this document are not intended to be
a minimum requirement that every building owner and manager should
implement for every building. Rather, the decisions concerning which
protective measures should be implemented for any building should
be based on several factors, including the perceived risk associated
with the building and its tenants, engineering and architectural
feasibility, and cost.
_________________________
*Note:
References to a release of CBR agent in this document will always
refer to an airborne CBR release.
BACKGROUND
Terrorism
events have increased interest in the vulnerability of U.S. workplaces,
schools, and other occupied buildings to CBR threats. Of particular
concern are the airflow patterns and dynamics in buildings, specifically
in the building heating, ventilating, and air conditioning (HVAC)
systems. These systems can become an entry point and a distribution
system for hazardous contaminants, particularly CBR agents. Building
owners need reliable information about how they can (1) modify their
buildings to decrease the likelihood or effects of a CBR incident
and (2) respond quickly and appropriately should a CBR incident occur.
Comprehensive guidance is needed in several areas, including:
How
to modify existing buildings for better air protection and security.
How
to design new buildings to be more secure.
What
plans building managers should prepare in advance to help them
make effective decisions in the midst of a CBR incident.
PREPARATORY
RECOMMENDATION—
KNOW YOUR BUILDING
While
more comprehensive guidance is being developed, this document focuses
on the shorter-term goals of identifying those protective actions
that you can take immediately. But it recognizes that some recommendations
may not be feasible for you or in all situations.
In
initiating any plan to modify building system design or operation,
an important first step is to understand these systems: How were
they intended to operate? How do they currently operate?
Getting
to know your building may best be handled by conducting a walk-through
inspection of the building and its systems, including the HVAC,
fire protection, and life-safety systems. During this inspection,
compare the most up-to-date design drawings available to the operation
of the current systems.* This step may require, or benefit from,
the assistance of qualified outside professionals. Without this
baseline knowledge, it is difficult to accurately identify what
impact a particular security modification may have on building operation.
While it is important to understand how the existing building systems
function, the systems need not operate per design before you implement
security measures. A partial list of items to consider during your
building walk-through includes:
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*Note: If sufficient questions or surprises arise
from the building walk-through, an independent evaluation by a qualified
HVAC professional should be used to establish a useful baseline.
What
is the mechanical condition of the equipment?
What
filtration systems are in place? What are their efficiencies?
Is
all equipment appropriately connected and controlled? Are equipment
access doors and panels in place and appropriately sealed?
Are
all dampers (outdoor air, return air, bypass, fire and smoke)
functioning? Check to see how well they seal when closed.
How
does the HVAC system respond to manual fire alarm, fire detection,
or fire-suppression device activation?
Are
all supply and return ducts completely connected to their grilles
and registers?
Are
the variable air volume (VAV) boxes functioning?
How
is the HVAC system controlled? How quickly does it respond?
How
is the building zoned? Where are the air handlers for each zone?
Is the system designed for smoke control?
How
does air flow through the building? What are the pressure relationships
between zones? Which building entryways are positively or negatively
pressurized? Is the building connected to other buildings by
tunnels or passageways?
Are
utility chases and penetrations, elevator shafts, and fire stairs
significant airflow pathways?
Is
there obvious air infiltration? Is it localized?
Does
the system provide adequate ventilation given the building’s
current occupancy and functions?
Where
are the outdoor air louvers? Are they easily observable? Are
they or other mechanical equipment accessible to the public?
Do
adjacent structures or landscaping allow access to the building
roof?
SPECIFIC
RECOMMENDATIONS
The
recommendations can be divided into four general categories: (1) things
not to do; (2) physical security; (3) ventilation and filtration;
and (4) maintenance, administration, and training. Some of these items,
such as securing mechanical rooms, may be started prior to your completing
the recommendations in the "Know your building" section.
Items within each of the four categories are listed in the order of
priority. Items considered to be highly critical are identified by
“***” next to the number. As you review these recommendations,
consider their potential implications upon the contract language necessary
for existing and future service contracts. A brief discussion of the
four categories and some commonly considered recommendations follow.
Things
not to do
More
than anything else, building owners and managers should ensure that
any actions they take do not have a detrimental effect on the building
systems (HVAC, fire protection, life safety, etc.) or the building
occupants under normal building operation. Some efforts to protect
the building from a CBR attack could have adverse effects on the building's
indoor environmental quality. Building owners and managers should
understand how the building systems operate and assess the impact
of security measures on those systems.
***1.
DO
NOT PERMANENTLY SEAL OUTDOOR AIR INTAKES. Buildings require
a steady supply of outdoor air appropriate to their occupancy
and function. This supply should be maintained during normal
building operations. Closing off the outdoor air supply vents
will adversely affect the building occupants and likely result
in a decrease in indoor environmental quality and an increase
in indoor environmental quality complaints.
***2.
DO
NOT MODIFY THE HVAC SYSTEM WITHOUT FIRST UNDERSTANDING THE EFFECTS
ON THE BUILDING SYSTEMS OR THE OCCUPANTS. This caution directly
relates to the recommendation that building owners and managers
should understand the operation of their building systems. If
there is uncertainty about the effects of a proposed modification,
a qualified professional should be consulted.
***3.
DO
NOT INTERFERE WITH FIRE PROTECTION AND LIFE SAFETY SYSTEMS. These
systems provide protection in the event of fire or other types
of events. They should not be altered without guidance from a
professional specifically qualified in fire protection and life
safety systems.
Physical
Security
Preventing
terrorist access to a targeted facility requires physical security
of entry, storage, roof, and mechanical areas, as well as securing
access to the outdoor air intakes of the building HVAC system. The
physical security needs of each building should be assessed, as threat
of a CBR attack will vary considerably from building to building.
For example, the threat to a large corporate headquarters may be considered
greater than the threat to a small retail establishment. Some physical
security measures, such as locking doors to mechanical rooms, are
low cost and will not inconvenience the users of the building. These
types of measures can be implemented in most buildings. Other physical
security measures, such as increased security personnel or package
x-ray equipment, are more costly or may inconvenience users substantially.
These measures should be implemented when merited after consideration
of the threat and consequences of a terrorist attack. Building owners
and managers should be familiar with their buildings and understand
what assets require protection and what characteristics about the
building or its occupants make it a potential target. By first assessing
the vulnerabilities of facilities, building owners and managers can
address physical security in an effective manner. While the identification
and resolution of building vulnerabilities will be specific to each
building, some physical security actions are applicable to many building
types. These include:
***1.
PREVENT
ACCESS TO OUTDOOR AIR INTAKES. One of the most important steps
in protecting a building’s indoor environment is the security
of the outdoor air intakes. Outdoor air enters the building through
these intakes and is distributed throughout the building by the
HVAC system. Introducing CBR agents into the outdoor air intakes
allows a terrorist to use the HVAC system as a means of dispersing
the agent throughout a building. Publicly accessible outdoor air
intakes located at or below ground level are at most risk—due
partly to their accessibility (which also makes visual or audible
identification easier) and partly because most CBR agent releases
near a building will be close to the ground and may remain there.
Securing the outdoor air intakes is a critical line of defense
in limiting an external CBR attack on a building.
Relocate
outdoor air intake vents.
Relocating accessible air intakes to a publicly inaccessible
location is preferable. Ideally, the intake should be located
on a secure roof or high sidewall. The lowest edge of the outdoor
air intakes should be placed at the highest feasible level above
the ground or above any nearby accessible level (i.e., adjacent
retaining walls, loading docks, handrail). These measures are
also beneficial in limiting the inadvertent introduction of
other types of contaminants, such as landscaping chemicals,
into the building.
Extend
outdoor air intakes.
If relocation of outdoor air intakes is not feasible, intake
extensions can be constructed without creating adverse effects
on HVAC performance. Depending upon budget, time, or the perceived
threat, the intake extensions may be temporary or constructed
in a permanent, architecturally compatible design. The goal
is to minimize public accessibility. In general, this means
the higher the extensions, the better—as long as other
design constraints (excessive pressure loss, dynamic and static
loads on structure) are appropriately considered. An extension
height of 12 feet (3.7 m) will place the intake out of reach
of individuals without some assistance. Also, the entrance to
the intake should be covered with a sloped metal mesh to reduce
the threat of objects being tossed into the intake. A minimum
slope of 45° is generally adequate. Extension height should
be increased where existing platforms or building features (i.e.,
loading docks, retaining walls) might provide access to the
outdoor air intakes.
