How does a wet cloth really help (scientifically) to survive an airplane crash?

"Ann Marie Brest" wrote in message ...
On Thu, 15 May 2014 20:16:19 -0400, Frank wrote:

What's the wet cloth (scientifically) doing?
http://www.faa.gov/pilots/safety/pil.../Smoke_Web.pdf

That nicely summarized FAA article explains:
- Smoke is a complex of particulate matter, invisible combustion gases & vapors suspended in the fire atmosphere.
- Inhalation of toxic gases in smoke is the primary cause of fatalities
- Carbon monoxide & hydrogen cyanide are the principal toxic combustion gases
- Carbon monoxide combines with the hemoglobin in blood and interferes with the oxygen supply to tissues
- Hydrogen cyanide inhibits oxygen utilization at the cellular level.
- Carbon dioxide is a relatively innocuous fire gas, increases respiration rate causing an increase in the uptake of other combustion gases
- Irritant gases, such as hydrogen chloride and acrolein, are generated from burning wire insulation
- Generally, carbon dioxide levels increase while oxygen concentrations decrease during fires.

And then finally, the article suggests:
- Cloth held over the nose and mouth will provide protection from smoke particulates;
- If the cloth is wet, it will also absorb most of the water-soluble gases (i.e., hydrogen cyanide & hydrogen chloride).

What's interesting is that the entire article doesn't discuss any dangers
of breathing smoke particulates, so, why it bothers to mention a dry cloth
is perplexing since we can safely assume that filtering out particulates is
merely a convenience, and not a safety issue.

So, now we're left with the a WET cloth absorbing water-soluble gases.
Of the two water-soluble gases, only hydrogen cyanide was listed in
the article as being a safety issue (the other water-soluble gas was
merely an irritant).

So, I guess we finally have the answer to "why the wet cloth?".

The WET CLOTH filters out (water soluble) hydrogen cyanide:
"Hydrogen cyanide poisoning signs & symptoms are weakness, dizziness, headache,
nausea, vomiting, coma, convulsions, & death. Death results from respiratory arrest.
Hydrogen cyanide gas acts rapidly. Symptoms & death can both occur quickly.

Logically, breathing through a wet cloth would also remove more particulate matter than through a dry cloth. Try blowing cigarette smoke thru a dry handkerchief and a wet one and you'll see a big difference.

On Fri, 16 May 2014 23:16:38 -0800, Guv Bob wrote:

Logically, breathing through a wet cloth would also remove more particulate
matter than through a dry cloth. Try blowing cigarette smoke thru a dry
handkerchief and a wet one and you'll see a big difference.

I have no problem with the logic - but it may also be an urban myth.

What should we conclude from the fact that absolutely ZERO articles have been
posted to this thread coming from the FAA to the airplane manufacturers to the
airline-safety fire departments to the airline-safety research universities
which back up this hypothesis?

To repeat clearly, absolutely ZERO articles have been posted to this thread
that report that smoke particles are a life-threatening danger to your
breathing in an airplane cabin fire and that a wet towel can ameliorate
that danger.

The purpose of this thread is stated in the subject line:
How does a wet cloth really help (scientifically) to survive an airplane crash?

To be clear here, I'd be *glad* to believe that a wet cloth helps save your
life by filtering out particles, but it's hard to believe that supposition
when not a single one of us (me included) can find a single reliable industry
reference that says so.

Ann Marie Brest wrote:
I'm not sure WHERE to ask this, but, how does a wet cloth
work in an airplane crash anyway?

In step 3 at 45 seconds into this video shows it in use:
http://www.youtube.com/watch?v=RXaTt...etailpage#t=49

What's the wet cloth (scientifically) doing?

My guess would be that the wet cloth catches many of the smoke particles, and
the water will cool the air you inhale.

On Thu, 15 May 2014 18:22:53 -0700, Bob F wrote:

My guess would be that the wet cloth catches many of the smoke particles,
and the water will cool the air you inhale.

Based on the one referenced FAA article, the dry cloth does nothing for
safety, but a wet cloth reduces the water-soluble hydrogen cyanide gases.

On Fri, 16 May 2014 03:30:48 +0000, Ann Marie Brest wrote:

Based on the one referenced FAA article, the dry cloth does nothing for
safety, but a wet cloth reduces the water-soluble hydrogen cyanide gases.

Armed with the new keywords "wet cloth hydrogen cyanide", I find more
on the toxicity of HCN over he

http://www.atsdr.cdc.gov/MMG/MMG.asp?id=1141&tid=249
"Hydrogen cyanide is readily absorbed from the lungs; symptoms of poisoning
begin within seconds to minutes. The odor of hydrogen cyanide is detectable
at 2-10 ppm (OSHA PEL = 10 ppm), but does not provide adequate warning of
hazardous concentrations. Perception of the odor is a genetic trait
(20% to 40% of the general population cannot detect hydrogen cyanide);
also, rapid olfactory fatigue can occur. Hydrogen cyanide is lighter than air.
Children exposed to the same levels of hydrogen cyanide as adults may
receive larger doses because they have greater lung surface area:body
weight ratios and increased minute volumes:weight ratios."

"Hydrogen cyanide acts as a cellular asphyxiant.
By binding to mitochondrial cytochrome oxidase, it prevents the utilization
of oxygen in cellular metabolism. The CNS and myocardium are particularly
sensitive to the toxic effects of cyanide."

"In the United States, antidotes for cyanide include amyl nitrite perles
and intravenous infusions of sodium nitrite and sodium thiosulfate,
which are packaged in the cyanide antidote kit."

But, what we need to know is how effective is the wet cloth in reducing
the hydrogen cyanide gases in the cabin air.

On Fri, 16 May 2014 03:41:06 +0000, Ann Marie Brest wrote:

Armed with the new keywords "wet cloth hydrogen cyanide", I find more
on the toxicity of HCN over he

And, here's what OSHA has to say about the dangers of HCN:
http://www.cdc.gov/niosh/docs/81-123/pdfs/0333.pdf

"[Hydrogen cyanide] is capable of bringing to a halt all
cellular respiration".

"A few inhalations of high concentrations of HCN may be
followed by almost instantaneous collapse and cessation
of respiration."

"270ppm HCN is immediately fatal to humans"
"181ppm HCN is fatal after 10 minutes"
"135ppm HCN is fatal after 30 minutes"
"110ppm HCN is fatal after 60 minutes"

"Humans tolerate 45ppm to 54ppm for 1/2 to 1 hour without
immediate or delayed effects, while 18ppm to 36ppm may
result in symptoms after exposure for several hours."

So, the key question is what the HCN concentrations are in
a typical airplane cabin fire?

On Fri, 16 May 2014 03:52:45 +0000, Ann Marie Brest wrote:

Armed with the new keywords "wet cloth hydrogen cyanide", I find more
on the toxicity of HCN over he

This flight safety PDF titled "Guarding the airways", is of interest:
http://flightsafety.org/download_fil...t06_p28-30.pdf

It mentions only that the "wet cloth" prevents irritation, which we're
not concerned with in this discussion.

They also explained that the "dry" heat of a cabin fire isn't of great concern:
"the human body’s upper airway naturally provides significant protection
to the lower airway and lungs against extreme heat from hot, dry air".

I'm pretty surprised about those findings, but they in this article
specifically about guarding your airway during an airplane cabin fire.

On Fri, 16 May 2014 03:30:48 +0000 (UTC), Ann Marie Brest
wrote:

On Thu, 15 May 2014 18:22:53 -0700, Bob F wrote:

My guess would be that the wet cloth catches many of the smoke particles,
and the water will cool the air you inhale.

Based on the one referenced FAA article, the dry cloth does nothing for
safety, but a wet cloth reduces the water-soluble hydrogen cyanide gases.

In WWI, early in the gas warfare stage before there were gas masks,
soldiers wet cloth with urine, which apparently absorbed chlorine and
phosgene and stuff pretty well. It's better than dying, I suppose.


--

John Larkin Highland Technology, Inc

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

On Thu, 15 May 2014 16:46:21 -0700, Ann Marie Brest
wrote:

I'm not sure WHERE to ask this, but, how does a wet cloth
work in an airplane crash anyway?

Why do they always boil water when a baby is coming?

Do babies drink coffee?

(on TV)

In step 3 at 45 seconds into this video shows it in use:
http://www.youtube.com/watch?v=RXaTt...etailpage#t=49

What's the wet cloth (scientifically) doing?

On Fri, 16 May 2014 04:24:46 -0700, micky wrote:

..snip....
Why do they always boil water when a baby is coming?

Do babies drink coffee?

(on TV)

...snip...

LOL! just popped out for a spot of tea?

However the heat from the hot water and towels dilates the cervix really
fast, but does increase the risk of infection.

Years ago, newspapers were used too, because they were steam press rolled
and sterilized, but not today.