I thought this video might pique your interest:
It's one of the videos about fire shelters I have to watch every year to keep my fire line qualifications. From 13:26 to 13:54 is where they talk about not wetting your clothing or handkerchief.
I'm not actually a firefighter. Most of the time I'm a Hydrologist. But sometimes they still call out "the militia". In 2008 we had a storm come through around June 20 with a bunch of lightning and started 400 fires in one night. We got most of them out in a day or two, but some burned together and some burned until it snowed in November. I worked 6 days a week for 8 weeks that summer. Fortunately, I don't have to swing a tool on The Line anymore, but I still need to be Red-Carded so I can go where I need to unescorted on the fire.
Anyway, here's my reference for my remarks (told you I was a scientist!) and frankly, I thought you might like it.
Hi Adam, thanks a lot for sharing your knowledge. Those fire shelters sure are something. They seem to have outstanding insulation, seems like a good shelter for extreme cold weather as well.
New Generation Fire Shelter with Case - Large
Use a Wet Cloth or Not?
The video above clearly explains that when trapped by fire and especially when fighting heat, a wet cloth will do more harm than good because it transmits heat better and the vapor burns your respiratory system. Water evaporates at 100 Cº, so we’re talking about some serious heat here. This would be the case of someone trapped in a forest fire or otherwise surrounded by burning flammable material. Having said that, if the threat you are dealing with is smoke rather than heat this may not be the case.
During World War I, British troops used clothes soaked with urine against chemical attacks (chlorine). At the same time many seem to have died because of the use of poorly designed wet cotton pads intended to be used as filters. Soldiers could not breathe through these when soaked with water. The effectiveness of a wet cloth over your mouth and nose is limited, yet it is still recommended in some cases:
"According to the fire safety guidebook Get Out Alive, which is endorsed by the U.S. Fire Administration, the recommended and almost universally endorsed method of filtering smoke during a fire is to place a wet cloth over the nose and mouth before escaping. The wet cloth absorbs some of the smoke particles and filters noxious substances in the smoke, thereby reducing smoke inhalation. While the use of a wet cloth will not eliminate smoke inhalation, its purpose is to reduce smoke inhalation for a sufficient amount of time to escape the smoky condition. The more time that is available to the person to escape before being overcome by smoke, the greater the likelihood of survival."http://www.surechem.org/index.php?Action=document&docId=2950437&db=USPTO&tab=desc&lang=&db_query=0%3A%3A0%3A%3A0%3A&markupType=all
The FAA makes a similar recommendation:
“A wet cloth held over the nose and mouth provides some protection from smoke inhalation”http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Smoke_Web.pdf
Another common event during club fires seems to be that as the sound insulation material and various plastic decorations start burning, they start dropping over victims in ignited melted form. Some accounts from “Republica Cromagnon” nightclub victims indicate that burning plastic would shower them as they escaped, dropping from the roof, in some cases igniting their hair. In this case I believe that if you do have a bottle or cup of water already at hand, soaking your head and clothes as you evacuate may help.
So, do you use a wet cloth as a respirator or not? The answer is, it depends. If you are mostly dealing with smoke (burning plastic, carpet, etc), a wet cloth over your nose and mouth will help provide some protection. If the fire is closing in and the heat is your greatest enemy, then do not use it since it may do more harm than good. With flames closing in around you the soaked cloth around your head and upper torso may prevent your hair and clothes from catching fire. Typical clothes made of cotton and nylon are highly flammable. Either way, your priority should be escaping the fire, not finding water to soak a tshirt or other cloth.