Biomedical Engineering Reference
In-Depth Information
dampers, especially those controlling the
flow of outdoor air (in the event of an
exterior CBR release). When the HVAC
system is turned off, the building pressure
compared to outdoors may still be nega-
tive, drawing outdoor air into the building
via many leakage pathways, including the
HVAC system. Consideration should be given
to installing low leakage dampers to minimize
this flow pathway. Damper leakage ratings
are available as part of the manufacturer's
specifications and range from ultra-low to
normal categories. Assuming that you have
some warning prior to a direct CBR release,
the speed with which these dampers respond
to a “close” instruction can also be important.
From a protective standpoint, dampers that
respond quickly are preferred over dampers
that might take 30 seconds or more to respond.
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1. Emergency plans, policies, and procedures.
All buildings should have current emergency
plans to address fire, weather, and other
types of emergencies. In light of past U.S.
experiences with anthrax and similar threats,
these plans should be updated to consider
CBR attack scenarios and the associated
procedures for communicating instructions
to building occupants, identifying suitable
shelter-in-place areas (if they exist), iden-
tifying appropriate use and selection of
personal protective equipment (i.e., clothing,
gloves, respirators) and directing emergency
evacuations. Individuals developing emer-
gency plans and procedures should recog-
nize that there are fundamental differences
between chemical, biological, and radiolog-
ical agents. In general, chemical agents will
show a rapid onset of symptoms, while the
response to biological and radiological agents
will be delayed.
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Issues such as designated
areas and procedures for chemical storage,
HVAC control or shutdown, and commu-
nication with building occupants and emer-
gency responders, should all be addressed.
The plans should be as comprehensive as
possible, but, as described earlier, protected
by limited and controlled access. When appro-
priately designed, these plans, policies, and
procedures can have a major impact upon
occupant survivability in the event of a CBR
release. Staff training, particularly for those
with specific responsibilities during an event,
is essential and should cover both internal
and external events. Holding regularly sched-
uled practice drills, similar to the common
fire drill, allows for plan testing, as well as
occupant and key staff rehearsal of the plan,
and increases the likelihood for success in
an actual event. For protection systems in
which HVAC control is done via the energy
management and control system, emergency
procedures should be exercised periodically
to ascertain that the various control options
work (and continue to work) as planned.
5.
Building air tightness
. Significant quantities
of air can enter a building by means of infil-
tration through unintentional leakage paths in
the building envelope. Such leakage is of more
concern for an exterior CBR release at some
distance from a building, such as a large-
scale attack, than for a directed terrorist act.
The reduction of air leakage is a matter of
tight building construction in combinationwith
building pressurization. While building pres-
surization may be a valuable CBR-protection
strategy in any building, it is much more likely
to be effective in a tight building. However,
to be effective, filtration of building supply air
must be appropriate for the CBR agent intro-
duced. Although increasing the air tightness of
an existing building can be more challenging
than during new construction, it should still be
seriously considered.
Maintenance, Administration, and Training
Maintenance of ventilation systems and training
of staff are critical for controlling exposure to
airborne contaminants, such as CBR agents.
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Note
: Additional information on CBR agents may be found via the references at the end of this document.
