protection for civil defense A nuclear, biological, and chemical (NBC) safe room
protects its occupants from inhaling harmful or deadly airborne toxins such as
very fine particles of radioactive fallout, biological toxins, and chemical agents.
In the past, the United States Government has poured extensive resources into
providing the best information for the protection of its citizens from NBC warfare
agents. This is not the case today.
For protection of the U.S. population
we have the government website: www.ready.gov. It suggests duct tape and plastic,
then wait for further official instruction. Although the tape and plastic method
would offer some immediate short term protection from low level toxins at low
concentrations, it would be, at best, a short term solution. Most governments
tend to only recommend emergency procedures that can be afforded by all their
As a contrast to most governments, both Switzerland and Israel
require, and subsidize the cost of, NBC safe rooms and blast shelters in residential
dwellings and commercial buildings. They have strict standards in place governing
both the construction of the room and the ventilation equipment protecting the
For protection of some of our military personal and government officials,
the U.S. Department of the Army - Corps of Engineers has standards by which NBC
airborn toxic free areas must comply. These standards dictate the differential
pressure (overpressure) in the safe room (protected space) as well as the design
of the NBC filter/ventilation system.
The main reasons why an un-pressurized
room will not protect the occupants for very long is that the room "breaths" -
in other words, it leaks air both in and out through the cracks as the external
atmospheric pressure fluctuates - due wind or other atmospheric variables like
temperature, and barometric pressure swings due to approaching weather fronts.
Air constantly tries to normalize its pressure and temperature between different
variants - as it does this, it brings with it whatever that air contains. Also,
in a sealed room, there is no accommodation to replenish oxygen and expel the
exhaled carbon dioxide of the occupants.
In order to create and maintain
overpressure as well as give the required air exchanges to support the air supply
needs of the sheltered occupants, a safe room must be equipped with true positive
pressure NBC filter/ventilation unit and a means of a metering the exhaust air
out of the protected space.
The Safe Cell features a filter bank
that is designed to protect against all known airborne toxins including nuclear
fallout, radioactive iodine, weaponized biological carcinogens, and warfare gases
such as sarin, VX, and tabun. The entire system has been designed to meet the
critical requirements in the United States Army Corps of Engineers Technical Letter