- It doesn't help that this "Threat Condition Orange"
perfectly coincides with the administration's desperate attempts to link
al Qaeda with Saddam Hussein, but let's leave politics aside for the moment.
-
- Houston press has reported that Lowe's and Home Depot
stores throughout Harris County have sold out of the plastic sheeting,
duct tape, and other supplies recommended by the Office of Homeland Defense
(OHD) in order for citizens to be better prepared in the event of an terrorist
act. It's the same all over the nation.
-
- This is a very serious health issue.
-
- "Place a dry cleaning bag over your head and await
further instructions." This may as well have been the instructions
by the time they filtered down to Betty Sue in Omaha. But we all know Betty
Sue doesn't have anything to worry about, does she? Well, she does if she
follows the instructions from OHD.
-
- The cause for most concern is the OHD plan for "What
to do during a chemical or biological attack":
-
-
- Seek shelter in an internal room, preferably one without
windows. Seal the room with duct tape and plastic sheeting. Ten square
feet of floor space per person will provide sufficient air to prevent carbon
dioxide build-up for up to five hours.
-
-
- And Good Morning America's Home Improvement Editor, Ron
Hazelton, assured his viewers:
-
-
- Don't worry about running out of air. Every ten square
feet of floor space will last an adult about 5 hours. And don't leave the
room until you get instructions from the Emergency Broadcast System to
do so.
-
- But notice the discrepancy in the phrases "to prevent
carbon dioxide build-up" and "don't worry about running out of
air." Hazelton is actually correct (probably accidentally) that the
amount of oxygen corresponding to a ten square foot space is probably sufficient
(though marginal) to sustain an adult for about five hours, but the critical
issue is not oxygen consumption, but carbon dioxide generation and accumulation.
The OHD statement is correct in identifying carbon dioxide accumulation
as a concern, but its conclusions are surprising, to say the least.
-
- Assuming an eight-foot ceiling (yielding eighty cubic
feet per person) and a subject metabolic rate of 800 BTU/hr, after five
hours the partial pressure of carbon dioxide (ppCO2) would be ~67 mm Hg
(if the initial ppCO2 were zero). It cannot be understated: this is very
high.
-
- (Note: 800 BTU/hr (3.36 kcal/min) is not unreasonable
for a very excited person in a hot and humid enclosure with elevated carbon
dioxide (more on that in a moment). For this case, a bare (but irresponsible)
minimum might be 600 BTU/hr (corresponding to a ppCO2 level of 50 mm Hg
after five hours). Consider that NASA Environmental Control and Life Support
(ECLS) engineers typically assume a waking metabolic rate of 450 BTU/hr
for moderate intravehicular activity, and this is with very physically
efficient subjects (astronauts) not using major muscle groups (e.g., legs)
in microgravity.)
-
- Keep in mind that the maximum operational limit for the
Shuttle Orbiter is 7.6 mm Hg, and is actually lower for the International
Space Station. The NASA Spacecraft Maximum Allowable Concentration (SMAC)
for carbon dioxide is 10.0 mm Hg for a one-hour period. Similar values
can be found among the literature of the various military branches.
-
- The NASA Bioastronautics Data Book (Second Edition, pp.
48-49) indicates that after only 80 minutes, at a ppCO2 level of ~18 mm
Hg, the subject can experience "mental depression, headache, dizziness,
nausea." At ~45 mm Hg (after 80 minutes), the subject experiences
"marked deterioration leading to dizziness and stupor, with inability
to take steps for self preservation. The final state is unconsciousness."
(The level in our case would not reach 45 mm Hg after 80 minutes, but the
threshold of the aforementioned symptoms would be at a much lower CO2 level
at the end of five hours.)
-
- Industry literature is similar.
-
- The W.E. Kuriger Associates web page titled "Carbon
Dioxide Fact Book," states that,
-
-
- Several studies have indicated that CO2 does not seriously
impact human health until levels reach approximately 15,000 ppm [7.5 mm
Hg]. At extremely high levels, i.e., 30,000 ppm [15 mm Hg] (these concentrations
are usually never reached in a standard home), the symptoms can include
nausea, dizziness, mental depression, shaking, visual disturbances and
vomiting. At extremely high levels, loss of consciousness may occur. Finally,
CO2 is an asphyxiate, a condition in which an extreme decrease in the amount
of oxygen in the body, accompanied by an increase of carbon dioxide, leads
to loss of consciousness or death. Concentrations of 100,000 ppm [50 mm
Hg] or more of CO2 can produce unconsciousness or death.
-
-
- And carbon dioxide is hardly the only physiological concern.
-
- One would probably pass out from heat exhaustion before
he passed out from exposure to high carbon dioxide concentrations.
-
- It's probably not a bad assumption to consider the system
adiabatic (no heat transfer - there would be very little heat transfer
via conduction, which is the only mechanism for heat transfer to the environment
in this scenario), and considering the thermal capacitance of the subject
(the thermal capacitance of the surrounding air is only about 1% of that
of the subject), suffice to say that the subject would have very serious
core temperature problems long before five hours time (a three, four degree
elevation per hour?)
-
- And within about ten to fifteen minutes after being in
this enclosure the air would become saturated, that is, 100% relative humidity
(and condensate would start forming on the plastic). As the air temperature
and humidity increases (deteriorating the mechanisms for rejecting the
subject's metabolic heat), and carbon dioxide levels increase, and as oxygen
is depleted (at the end of five hours, at 800 BTU/hr the subject would
be at an altitude equivalency of ~19,000 feet (0.47 atm.), at 600 BTU/hr
~14,000 feet (0.60 atm.)), his metabolic rate will increase, in turn increasing
the metabolic heat and perspired and respired water vapor he generates,
creating a vicious cycle.
-
- And, of course, children and elderly can withstand much
less of this kind of environment than adults.
-
- Perhaps the worst aspect of the dissemination of this
information is that the balance of the press, including network news broadcasters,
didn't even mention a time limit at all.
-
- Other aspects of the OHD statement are very odd - how
many folks are wealthy enough to have an inside room with no windows (other
than a closet, which would, according to their recommendations, only be
sufficient for one person)?
-
- And plastic sheeting? That's awfully vague. Surely there
are permeability and robustness issues here. The Washington Post reported
that in a local D.C. hardware store "plastic dropcloths were being
evaluated with one aim in mind: Would they work to seal a room?" Good
question, but not likely.
-
- Considering that only a very tiny proportion of the population
(and obviously no one at the Office of Homeland Security) are trained to
make these calculations and decisions, and remembering that a significant
portion of the population doesn't know their "right hand from their
left," may God bless them, the instructions from the OHD are cause
for very serious concern.
-
- So please give this wide circulation - there is a high
likelihood that there are plenty of folks already out there sitting in
an enclosure that they believe to be safe, unknowingly endangering the
lives of themselves and their children.
-
- February 14, 2003
-
- Brian Dunaway [send him mail] is a chemical engineer
and a native Texan.
-
- Copyright © 2003 LewRockwell.com
-
-
-
- http://www.lewrockwell.com/dunaway/dunaway21.html
-
-
- Comment
-
- From Jay Grimes
- 2-17-3
-
- Jeff,
-
- There is another issue that this article failed to mention
- the issue of air infiltration through the floor/sub-floor structure.
As the relative air pressure decreases through consumption over a 4-5 hour
period it will create a vaccum that will start drawing supposedly contaminated
air in through any floor or miniscule crack in the room. The only "safe"
option is a positive pressure air filtration/ventilation system.
-
- Jay Grimes
- Stuart, IA
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