We’ve been covering gas masks lately, everything from how to pick the best gas masks, types of respirators, and we even answered some of the most frequently asked questions. Well, this one’s for all you nerds out there because today we’re answering the question: how does a gas mask work? More specifically, we’re covering the science behind gas mask filters.
How Gas Mask Filters Work
Gas mask filters, also referred to as cartridges, work a few different ways. Depending on your filter’s manufacturing will depend on how it keeps you breathing that good clean air. Yes, ultimately, all filters do the same thing; they purify the air so you can breathe safely. Some have a combination of filtering techniques, while others only implement one. Depending on the type of filter you have, it may use one or all: particle filtration, absorption/adsorption, and/or chemical neutralization.
Particle Filtration
Think of it this way. If you’re sawing wood, all these little pieces of sawdust go everywhere. It’s not good to breathe in those tiny particles of wood. So, you might put a piece of cloth, construction mask, or paper mask around your mouth and nose. These materials prevent those particles from entering your lungs through your mouth or nose. This is particle filtration.
However, the particles found in biological war are much smaller than sawdust particles. Therefore, you need a better filter. While they work the same, a gas mask filter intended for CBRN (chemical, biological, radiological, and nuclear) agents has more adequate filtration. This is because those particles are so much smaller, micron-size particles that would get through a cloth or paper mask.
Think of these filters as pores. Your filter has these very, very tiny holes that you can’t see, but they’re there. The smaller the pore, the less that gets through. However, anything smaller than that pore will get in (which is why some filters use more than this technique to protect your lungs).
While we’re on the topic of pores, let’s talk about how pores get clogged. Imagine the pores on your face. Your pores collect dirt and grime. When your pores get clogged, blackheads can be seen. Since your filter has pore-like holes, that means they too get clogged, just like the pores on your face.
However, unlike facial pores, when the pores in your gas mask get clogged, it can make it quite difficult to breathe. When this happens, you need to change out your filters.
Particle filtration is used for biological agents.
Absorption/Adsorption
Particle filtration is excellent for biological agents, things like anthrax. However, what about chemicals? Chemicals are usually spread through mist or vapors, and they can be much smaller than what the particle filtration processes can prevent from getting through. But you know what’s needed when particle filtration won’t work? A process known as chemical absorption or chemical adsorption, hopefully (depending on the threat, of course).
Chemical Absorption
Chemical absorption is due to something called carbon filtration or activated charcoal. And activated charcoal is a result of oxygen-treated charcoal. This activated charcoal opens up the charcoal’s tiny pores and creates little holes to collect (absorb) the organic chemicals.
Imagine it like this. If you walk through an open field, flat and with nothing obstructing your path, you’ll easily get through the area. However, imagine that same field, but millions of holes, all big enough to swallow you up. If you start running through that field, you’ll end up falling in one of those holes, and you’ll be trapped. Chemical absorption is similar. There are all these tiny holes, but big enough to swallow up those nasty chemicals. As the chemicals race through, they fall into these holes and get trapped.
Chemical Adsorption
You probably know what it means to absorb something, but what is adsorption? Adsorption is the attraction. Chemical adsorption is where the chemical is attracted to the filtering agent, which is the charcoal. The charcoal acts as a binding site, in which case you can imagine these little chemical vapors sticking to the charcoal. It’s kind of like those holes have tiny monsters in them, popping out to grab the chemical.
Here’s how I like to imagine it, on a much larger scale. Have you ever seen those velcro suits? You put on this suit and then jump at the velcro wall. When you jump into this wall, you stick to it. Similarly, chemicals like nerve agents adhere to the carbon surface and don’t get through to your lungs. If there weren’t any velcro, you’d just kind of fall off to the side.
Chemical Neutralization
Absorption and adsorption are great filtering techniques. However, what happens if the holes get filled up, and there’s no surface area for the chemicals to stick to, or the agent needing filtered is big enough to hop right over those holes? That’s where chemical neutralization comes into play.
You can imagine this like an army that made it over the wall. Since the chemicals couldn’t be stopped, they must be eliminated. And elimination works by using a chemical reaction. And what does that look like? Basically, two chemicals (the one in your filter and the one trying to get through your mask) contact one another. When the two chemicals meet, there is a reaction, and this reaction kills the chemical you don’t want to breathe in, such as chlorine.
How Does a Gas Mask Work?
Your filters are capable of doing the job, so long as your filter is rated for whatever the CBRN-type agent is. However, if your mask isn’t correctly fitted, it won’t work. This is because your gas mask will let the air bypass your filters. You need a proper seal to force the particles, mist, and or vapors to enter through the filter part. You get this by having a proper-fitting mask, which you can determine through a gas mask fit test.
To go with our imagination theme, you can think of the seal as such: You own a house. At night, you lock the front door. Locking the front door requires that a visitor knock, and in an ideal world, the only way they can get in is if you let them in. However, you also have a back door. If you forget to lock the back door, people can also enter through it and don’t have to worry about knocking.
The seal around your gas mask is the back door. If you don’t lock it, then those harmful chemicals can enter through the back door.
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