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Thai riot police women wear gas masks.

Riot police wear gas masks in Bangkok, Thailand.

Photograph by EPA/Corbis

Jaclyn Skurie

National Geographic

Published August 30, 2013

Hundreds of Israelis are lining up outside local distribution centers this week to collect protective gas masks following a series of reported chemical weapons attacks in Syria. If the United States does intervene in Syria, neighboring Israel fears being the target of a counterattack.

Speaking from the Department of State on Friday, Secretary of State John Kerry announced a death toll of 1,429 people from a Syrian chemical weapons attack, including at least 426 children. If Israel was caught up in this deadly chemical warfare, could gas masks provide effective protection to its people? (Realted: "Chemical Warfare, From Rome to Syria. A Time Line.")

To understand the workings behind a modern-day gas mask—an invention that dates back to World War I—National Geographic spoke with John Georgiadis, a professor of mechanical engineering at the University of Illinois, who researches filtration systems.

How is a gas mask made? Is it just like any other mask?

No. Assuming an attack is anticipated, a full-faced gas mask has two features that prevent us from inhaling potentially toxic contaminants in the air. They are barriers placed in the filter located on the snout of the mask.

The first is a particle filter which removes any bacteria in the inhaled air. There is essentially no chemistry involved here, just a physical barrier that forms a field between the toxins and the face. When a particle is inhaled, it hits the fibers on the filter and becomes tangled before it ever has the chance to reach the nose or mouth and move down to the lungs. (Related: "Why are Chemical Weapon Attacks Different?")

The second element is based on a chemical process called adsorption, and removes toxic molecules like the nerve gas Sarin. Through adsorption, a solid or a liquid can trap particles on its surface—analogous to the way a cigarette filter reduces the amount of toxins a person inhales when smoking.

To filter out harmful chemicals, most gas mask filters are made with activated charcoal, or oxidized charcoal. When charcoal is activated with oxygen, it becomes ripped with tons of "sticky" holes in each molecular structure just like chicken wire. Any toxins that pass through the charcoal become bonded to these holes, and are prevented from moving into the gas mask.

How effective is a gas mask in a situation of chemical warfare?

For the full-face mask, a rubber hood goes over the head and creates a tight connection with the face. Sometimes people don't put it on properly and gas can then go through those cracks.

Many chemical attacks also affect the skin. Even if your lungs are protected by a gas mask, your skin is not. There are nerve toxins that are meant to attach themselves to the skin. Simply washing the skin is not sufficient for protection.

Can a filter become clogged?

There is a tricky compromise between creating an efficient filter that catches 99.99 percent of the toxic particles while also leaving enough open pores to breathe through. The masks are only meant to be worn for a short amount of time before the filter ultimately clogs up.

You could create a huge filter, but carrying it around would be like having an elephant trunk on your face. You wouldn't be able to move very easily.

How long can you wear a gas mask?

These are not engineered for long-term living, and you could probably wear a gas mask for about three to four hours before having to change the filter. You must be trained to get the mask on and off, change the filter, and expose yourself briefly to whatever chemical is in the air. I did this once, and don't want to do it again. It is a terrible feeling when you can't breathe because you are afraid.

This interview has been edited and condensed.

Follow Jaclyn Skurie on Twitter.

5 comments
Connor Dobson
Connor Dobson

At the lab I work at we have to wear gas mask and biohazard suits to protect us, its a life saver if you ask me

ute hall
ute hall

im looking for the article you printed on phantom pain

Shane C.
Shane C.

Lots has changed since 1972. However, this was my experience with gas masking. The first time we entered the gas hut or room we had the masks on  then we took them off. We left the building and would be led back in with the room filled with gas and no mask on. We were told a 200lb man had approximately 15 seconds to mask, before he would lose consciousness or would vomit into his mask upon which he would drown in his own vomit. Once we masked we had to blow out very hard to clear the inside of the mask from the gas and hold our hand over the filter after and then remove it quickly, and start breathing normally once you stopped coughing and your eyes cleared form the burning. We gave ourselves an atropine injection before we suited up in coveralls. We buttoned up completely, but the area of our necks exposed to the gas was burned all around like a bad sunburn. Once we left the building the gas turned to powder like talca or baby powder and we had to help dust each other off. Then we removed all our contaminated clothes and went for a shower. I never did know what type of gas they used on us. Only we were being prepared for a mustard(nerve) gas fallout

mark nolan
mark nolan

I have had a gas mask at home for many years. I'm thinking that I may need an upgrade though.

Kate Dor
Kate Dor

It is not exactly true- Israels' Home Front Command guided us wear a gas mask for about six hours before having change the filter.

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