GAS MASK BUYER’S GUIDE
Gas Mask Buyer’s Guide
The history of gas masks is long and varied, in hopes of matching the threat from various different types of agents. Early “masks” were just wet sponges covering the user’s mouth and nose. As threats changed, so did the masks and the technology behind them. Lots of people are familiar with the M17 military gas mask, but like everything in life, filters and composition have improved. Today, the M17 is nothing more than a conversation piece since the filters contain chromium, which we now know to be a carcinogen.
The first question you should consider is whether you even need a gas mask. If the anticipated threat is simply riot control agents (RCA), then any of the masks listed here will be fine. And depending on how uncomfortable you want to be, so will a wet sponge. The penalty for exposure to RCAs is discomfort for a brief period of time.
If it’s something more nefarious, like VX nerve agent, then a mask is only the first step since the agent can also be absorbed through exposed skin. That type of threat requires full body protection and coverage — but level A to D chem suits are a topic for another day.
In this article, we’ll discuss two types of threats: CBRN (chemical, biological, radio- logical, and nuclear) and RCAs. Considering the nature of these hazards, only full-face respirators are considered. These types of agents not only affect your breathing, but they’re particularly good at disrupting your moist bits, like eyes, mouth, and nose. All of those areas need to be covered to be properly protected, hence the need for fullface protection.
Plenty of people lose their minds as soon as the “octopus” attaches to their face. Hyperventilating and feelings of claustrophobia are fairly common. So, if the facehugger creatures from the Alien franchise really freak you out, air-purifying respirators (APRs) will take some getting used to. Drawing breath will be harder in an APR — you’re pulling air through a fairly dense filter, so normal breathing will be affected. Add in any physical activity, and it only gets worse.
It goes without saying that you should be checked by a doctor to determine whether you’re healthy enough to wear a mask, how long you should wear it, and whether or not prolonged use might have adverse health effects. Most occupational health clinics can perform this type of checkup since they routinely do it for cops and occupations that require respirators.
Of course, if you’re faced with a situation where a mask is truly needed, you’ll need to weigh the potential health risk of wearing it versus that of exposure. The general health checkup is still important for training in a mask though, so please don’t neglect it.
Selecting a full-face mask isn’t enough on its own — you’ll also need to consider its level of protection. In conjunction with the type of filter chosen, the mask ’s materials are also important. Butyl rubber (BR) and silicone are the most common, with butyl rubber being more resistant to UV and different types of chemicals. BR and silicone are most common since they provide a great sealing surface as well as resistance to a large variety of agents.
Ideally, the mask you choose should accept filters with a 40mm NATO thread. This will allow you to choose from a variety of NATO filters. A NIOSH-rated (National Institute for Occupational Safety and Health) CBRN filter will handle damn near everything. The MSA Advantage doesn’t have this feature, so its value is diminished as a result. Filter adapters are available, but introduce an additional point of potential failure in a very important system. Masks are certified, but only filters are rated. To learn more about the accreditation system you can visit www.cdc.gov/niosh/npptl/topics/respirators/disp_part/default.html.
The upper portion of your mask should provide clarity of vision and keep peripheral vision obstructions to a minimum. It should be easy to don without a complex webbing system, and lastly it should be comfortable to wear for prolonged periods. A hydration tube port is always a welcome feature — in some hotter climates and more strenuous conditions it should be considered mandatory. Remember that you may not be able to take off the mask for several hours, and without a hydration port, you won’t be able to drink anything during that time. A CamelBak adapter is readily available for most masks with drinking tubes.
The addition of voice amplifiers and radio cables might also be mandatory depending on your task and purpose. And if you’re using it frequently for police or military operations, or if you’re really committed to making sure it can save your life, then you need to be clean shaven to ensure the best seal. Sorry neckbeard dudes, but no amount of Vaseline smeared into your beard will give you the same seal as bare skin.
All of the masks evaluated were size medium, and this author tested all of them for “fit factor” on an OHD Fit Testing Machine. The OHD machine is designed to test the overall fit of the mask on an individual user. The filter is removed, and the machine is hooked to the filter port of any mask with 40mm threads. Once hooked up, the wearer goes through a series of tests while holding their breath. The machine purges the air from the mask and creates negative pressure. Sensors determine the overall “fit” of the mask to the wearer. This takes the guessing game out of what size is best for you, and helps determine the best size based on the shape of your face and head. The test procedure includes standing straight up, bending over at the waist, vigorous shaking of the head from left to right, and so forth.
You’re allowed to breathe in between each test, but you must hold your breath for each event. The end result is either a pass or fail, and the machine will provide a number, or “fit factor.” The higher the number, the better the seal and fit of the mask to the user. If you don’t have access to a machine, a negative pressure test or the use of strongly scented sprays like Bitrex or banana oil are good alternatives. The latter items should be available through safety supply distributors that cater to industry professionals. We’ll explain negative pressure testing in a bit, but for now let’s talk about the masks that were tested and evaluated. A minimum point value of 500 is required to get a pass; there’s no maximum number that we’re aware of. The higher, the better.
With the exception of the Mestel mask, this author has worn all of these masks into RCA environments for prolonged periods of time during building searches for criminals. Agent exposure was CS and OC — in other words, tear gas and pepper spray. In most cases the agent was in both liquid and powder form, and usually both types of agents were deployed on the location. The Mestel mask was worn for a period of 90 minutes to test for comfort and weight, but due to the lack of a location to deploy live agents, no agent exposure test was performed.
In addition, we conducted peripheral vision measurements using a standard tape measure. These measurements were taken while standing with head straight up and then while casting eyes down to determine how far forward we could see on the ground without tilting the head. This is important if you’re navigating through a congested space, even more so in low light. We also took a measurement looking straight down at the ground with head tilted forward. This simulates having to climb down something or just looking for obstructions directly at your feet.
Lastly, we measured with head straight and then eyes moved hard left and right to determine how much peripheral vision was available. These measurements are indicated below by straight, downward, and peripheral vision loss, respectively. This was conducted using a tape measure with the base of the tape at the wearer’s feet. Zero inches would indicate no loss of vision and then extends out from there. So the higher the number, the further away the visible point is.
Negative Pressure Testing
While the OHD machine provides the best measurement of fit, negative pressure testing comes in second, followed by a squirt of Bitrex or banana oil as mentioned before. A negative pressure test is easy to perform and can be done every time you put the mask on to ensure you have a proper seal. If you think you’re already exposed, hold your breath first. Don the mask, cover the exhale port, and breathe out forcefully. This will vent the contaminated air that you just scooped onto your face. Immediately cover the filter inhale port and attempt to breathe in. You shouldn’t get any air.
If you do get air, the mask isn’t secured properly and is allowing air to pass — or you didn’t completely cover the filter inhale port. Reposition and try again. Adjust the head harness accordingly. If you still sense agent, vent the mask again using the procedure above, but don’t remove the mask. Start at step two. If you’re simply putting your mask on due to concern about possible agents being disseminated, there’s no need to hold your breath during the donning procedure.
If the eyepiece is fogging, it’s generally an indicator of a bad seal. Reposition and go through the aforementioned steps again. The mask is designed so that contaminated air gets pulled through the filter and cool air goes over the eyepiece to de-fog. The air is then drawn into the mouth/ nose piece, and you breathe the filtered air. When you exhale, diaphragms in the nose piece are sealed. This forces the condensation and exhaled air out of the exhale port. Breathe in and the diaphragm on the exhale port is sealed.
If you’re in a chemical environment and need to conduct a filter change, take a deep breath and hold it. Unscrew the old filter and screw on the new filter without taking a breath. Once the new filter is seated, cover the exhale port and forcefully breathe out. If you inadvertently breathe in with the filter off, you’ll draw contaminated air into the face piece. Once the new filter is on, breathe normally. It’s worth noting that this procedure is different if you have an Air Boss LBM. The LBM is designed so that when the filter is removed, a spring-loaded mechanism seals the mask. If you attempt to breathe in, you won’t get air until the new filter is seated. It goes without saying that you need to be able to conduct a filter change rapidly while wearing the mask in any condition.
Maintenance for all the masks is simple. Remove the filter. Filters can be exposed to rain and fog, but shouldn’t be submerged in water. Once a filter is removed from its foil pack, it’s certified for 15 minutes of use for the agents it’s designed to defeat. For riot control, you can reuse the same filter over and over until you start to sense agent. Then replace as necessary. For CBRN, you better have new ones in foil pack ready to go that aren’t expired, per the date on the package. If you don’t, use what you have, but you’ll be taking a chance.
Once the filter is removed, the whole mask can be dunked in warm soapy water and rinsed clean. Airdry and then use an appropriate lens cloth on the eyepiece. If the mask is contaminated with CBRN, you can’t just pop it of f and start cleaning it. You need to go through an entire decon process. For RCA, you can just clean it, but be careful about touching your eyes, face, and other sensitive areas until your hands are thoroughly washed as well.
For peace of mind, a certified CBRN filter from a reputable manufacturer will work for both CBRN and RCA. They are fairly big, however, so police officers may want a separate RCA-only filter as well as CBRN filters stored in foil packs. This keeps the good ones ready and the smaller, usually cheaper RCA filters for most common use.
This article covers just a small sampling of the many masks available on the market. Most of them were chosen with the fighting man’s needs in mind, but many of those same needs are common for the citizen. A base guideline would include: full face piece, 40mm thread compatibility, comfort, and hydration, with the cost factor considered after all the others. Anything manufactured prior to 2000 shouldn’t even be considered for purchase, as technology has advanced way too far to accept anything else.
A mask is also only the first step in protection. Dermal exposure is a concern for many CBRN agents, but that’s an entirely different topic. A tall optic mount for your rifle allows for faster and easier acquisition of sights, but a laser aiming device is best when wearing a mask. If the mask manufacturer makes a lens cover, they’re highly recommended to keep the viewport clear. Most do, and some even offer smoke, yellow, and laser safety lenses.
Lastly, if you’re considering starting a riot or helping to maintain a riot, and you’re reading this article to thwart law enforcement attempts to maintain the peace, then shame on you. No mask will protect you against a barrage of less lethal munitions or a pair of handcuffs.
OHD Fit Machine
Fitment is just one part of the overall puzzle in determining proper gas mask use. Have a doctor perform a thorough physical to ensure you’re healthy enough to use one. Photo courtesy of Avon Protection.
Filters with red circles highlighting protection level, CBRN, and CS/ CN/P100. P100 means it’ll filter particulates out of the air down to 1 micron in size. The width of a human hair is 75 microns. CN is a riot agent that’s no longer used due to its high carcinogen factor, but it’s still indicated on filters. OC is generally never listed as an RCA, even though you wouldn’t want to inhale it — OC is a derivative of hot peppers, thus it’s considered a food product not an “agent.”