We can survive three weeks without food, three days without water, but only three minutes without breathable air.
That's why gas masks can be a lifesaver in disasters, terrorist attacks, or nuclear meltdowns. But without the right filter, even the best gas mask is useless.
Fortunately, modern 40 mm gas mask filters are specialized to protect you from hundreds of toxins and airborne contaminants-ranging from chemical to biological, radiological, and even nuclear-all while fitting the same gas mask.
For example— a single type of filter can protect you from all of the contamination from a nuclear meltdown for up to 24 hours, while another filter could help you safely navigate the smoky environment of a house fire to reach safety.
But each gas mask filter has its limitations…
Each filter has a shelf life, classification, specs, and price. The craftsmanship of their construction matters just as much as the science behind their effectiveness.
Creating a working gas mask filter takes specialized knowledge of impregnating carbon with a key balance of metal salts and then treating the blend with chemicals to pass strict testing requirements.
These complicated factors are often overlooked by new and sometimes even experienced buyers. That mistake can cost you time and money…or something even more critical.
So, we will look at everything you need to know about gas mask filters: from their practical function and specifications to the logistics of storing them and, should the need arise, putting them to life-saving use.
We've assembled all the research you need to make an informed decision and give your family the protection they might need.
Let's get started…
Table of Contents
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01
Gas Mask Filters 101
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02
Filter Classification
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03
Filter Certification
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04
Top 3 Gas Mask Filters of 2023
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05
Filter Storage & Shelf Life
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06
Filters to Avoid
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07
Conclusion
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08
Gas Mask Filter FAQ
Gas Mask Filters 101
The history of gas masks and how gas mask filters became practically universal is something we've already covered in our Gas Mask Buyer's Guide, so we won't delve into that here.
On the other hand, modern gas mask filters are indeed a technological marvel.
It all starts with activated charcoal: a carbon filter media with an enormous surface area. There are approximately 130,000 square meters of surface area on just 100 grams of activated charcoal. It is carefully impregnated with a specific blend of metal salts and then treated and tested to ensure effectiveness.
Carbon impregnation is an exacting and skill-intensive process that takes years of mastery to consistently get right. Beyond science, it takes excellent craftsmanship and knowledge to do it correctly. This particular filter media is added to other layers with elements like microfiber filter paper that protects against dust and particulates.
The fiber density works as a fine mesh, reliably capturing the finest particles, including aerosols, smoke, microorganisms, and highly toxic elements. NBC filters are equipped with unique hydrophobic P3 class filter elements to ensure superior performance.
PRO TIP
Gas Mask Filter Function Basics
Gas mask filters rely on three chemical processes to provide clean air in even the most toxic environments.
Filtration
Filtration is the most basic process, separating solid particles and aerosols from breathable air using media like charcoal.
Physical adsorption
This happens when the captured substance condensates into the porous structure of the filter's activated carbon. This process actually captures gas molecules as they pass through, neutralizing threats.
Chemisorption
This occurs when physical adsorption meets the impregnated chemicals in a filter's activated carbon. Even the most toxic elements can be momentarily captured during this process, forced to interact with impregnated elements, and immediately neutralized.
Due to the precise nature of filter construction and the mechanics involved, there are a few key classes of filters you'll notice immediately:
1. Particle filters
Particle filters use primary filter media like Class 16 fiber paper to filter out common toxins. They're basic and affordable due to their simple construction, and these are more often used for construction and demolition.
2. Gas filters
Gas Filters use the impregnated carbon we discussed to provide more comprehensive protection from airborne threats. Note that these gas filters typically lack the mechanical filter media of particle filters.
3. Combined filters
Combined filters are, as the name implies, a combination of gas and particle filters to provide more comprehensive protection from a wider variety of threats than either can provide alone.
4. Special filters
Special filters - like most CBRN filters on the market today, protection is even higher, with safeguards against organic substances with low boiling points, including mercury, COx, NOx, and radioactive metal iodide.
To produce a modern gas mask filter takes remarkable skill and expertise. Fortunately, it couldn't be any easier to put one to use.
Gas mask filters are easy to carry, use and store, with a shelf life that can stretch into decades. Depending on the specific filter, they can provide up to 40 hours of practical protection from airborne contaminants and toxins.
Any worthwhile gas mask filter will have these details in the included documentation. This can make logistics straightforward, as seen in the Storage & Shelf Life section below.
Many filters have the same round shape and size that you probably already know. Inside, each filter has a unique combination of chemical and mechanical media to filter out particulates and provide the user with breathable air even in extreme environments.
Due to the complicated nature of how these filters are built, there's no "one size fits all" solution, so filters are classified based on the protection they provide—typically designated by a series of numbers and (sometimes) color-coded bands (per standard EN 14387+A1). More on that in Filter Classification below.
It's important to note that these color-coding systems are primarily used for easy identification by industrial workers, so you won't see them on all filters (they're noticeably absent on the NBC-77 SOF filter, for example, which is all grey). Most (but not all) of the gas mask filters you'll see on the market today are threaded to screw into gas masks with one of two popular formats known as 40 mm NATO and GOST.
As the name implies, 40 mm NATO is the filter standard used by NATO and US armed forces (conforming to the specifications of STANAG 4155 EN148-1), making these filters a popular and readily available choice for law enforcement, private military contractors, and civilians.
For 99% of concerned civilians, 40 mm NATO filters are what you want. It's an actively policed and maintained format associated with other NATO gas mask filter requirements and regulations. So even if you're paying a few bucks more, you know what you're getting. We'll cover a few of the best NATO filters for your money in our Popular Filter Choices section below.
GOST, on the other hand, is the competing Russian standard for gas masks and filters. Filters like the VK-530 can be GOST-certified using the standard NATO 40mm threading, giving you a practical and budget-friendly alternative that works with your favorite gas masks.
GOST testing is practically a copy of Europe's CE testing, ensuring you get a solid product. It's essential to avoid expired GOST filters or anything from the 80s and 90s. These older filters can contain chromium or asbestos, which can be seriously hazardous.
GOST, on the other hand, is the competing Russian standard for gas masks and filters. Filters like the VK-530 can be GOST-certified using the standard NATO 40mm threading, giving you a practical and budget-friendly alternative that works with your favorite gas masks.
More on that in the Filters to Avoid section below.
Some newer gas mask filters (like those used with the M50) use a proprietary thread, meaning they'll only work with a specific mask. This can provide some key advantages but can also limit your choice of filters—at a higher cost than civilian-ready CBRN masks and filters.
PRO TIP
Key things to remember about gas mask filters
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Always inspect your filters! Gas mask filters are often stored for months or even years, and they must be ensured before use to ensure the housing is intact, and the filter itself hasn't been damaged.
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Gas masks & filters have a minimum required oxygen level depending on the filter and its specifications. In many cases, this means at least 17% ambient oxygen levels (19.5% if in accordance with NIOSH) to function; any less requires a self-contained breathing apparatus (SCBA).
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The expected concentration of harmful substances in the air, with regard to the period of maximum possible use, should be 1,000 ppm (0.1% volume) for a Class 1 filter, 5,000 ppm (0.5% of volume) for a Class 2 filter; 10,000 ppm (1% of volume) for a Class 3 filter. If concentrations exceed a filter's certifications, the filter may fail.
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If a gas mask filter is used against radioactive substances, mercury or other highly toxic substances, low-boiling organic substances, tear-producing and irritating substances, dangerous microorganisms, NOx, or carbon monoxide, it cannot be reused!
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Always use a filter with the P3 or P3D filter element against solid and liquid particles, microorganisms, viruses, smoke, etc.
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The "Reactor" certification is critical for any filter you plan to use in the aftermath of a nuclear meltdown or explosion. This certification ensures a filter will protect you from the threat of radioactive iodine.
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The maximum useful life of a filter against mercury vapors is legislatively defined by European standards as 50 hours.
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Gas mask filters cannot be cleaned, so do not apply pressurized air or water.
There are plenty of choices when picking your mask and filter. If you feel overwhelmed, step back and ask what you need from your gas mask and filter setup. Will you use your gas mask filter on the job?
Filter Classification
As mentioned above, canister gas mask filters offer versatile and reliable protection from hundreds of contaminants, toxins, and particles. But these filters are still limited by practical concerns like size and weight and are porous enough to comfortably breathe through them.
That's why individual filters are classified and coded according to a strict system, informing users of the types of toxins and compounds each filter can protect against.
| Color | Mask type | Application | Class | Gas Concentration | Standard |
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| P3 | Particles | 1 2 3 |
low efficiency medium efficiency high efficiency |
EN143 | |
| A | Organic gases & Vapours-boiling point > 65°C | 1 2 3 |
1000 ML/M3 5000 ML/M3 10000 ML/M3 |
EN405 Disposable EN14387 |
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| A | Organic gases & Vapours-boiling point > 65°C | 1 2 3 |
1000 ML/M3 5000 ML/M3 10000 ML/M3 |
EN14387 | |
| B | Inorganic gases and Vapours (not CO), i.e chlorine, H2S, HCN,… | 1 2 3 |
1000 ML/M3 5000 ML/M3 10000 ML/M3 |
EN14387 | |
| EA | Acid gases | 1 2 3 |
1000 ML/M3 5000 ML/M3 10000 ML/M3 |
EN14387 | |
| K | Ammonia and organic derivatives | 1 2 3 |
1000 ML/M3 5000 ML/M3 10000 ML/M3 |
EN14387 | |
| AX | Certain organic compounds with boiling point <65°C - of low boiling substances groups 1&2 | gr.1: 100ml/m3 max 40' gr.1: 100ml/m3 max 20' gr.2: 1000ml/m3 max 60' gr.2 5000 ml/m3 max 20' |
EN371 | ||
| NO (+P3) | Nitrogen oxides e.g NO, NO2, Nox | Maximum allowed time of use: 20min | EN141 | ||
| Hg (+P3) | Mercury vapours | Maximum allowed time of use: 50 hrs | EN141 | ||
| CO*C | Carbon monoxide | Local guidelines | DIN 3181* | ||
| Reactor P3 | Radioactive iodine | Local guidelines | DIN 3181* | ||
You don't necessarily have to memorize these classifications, but it's necessary to keep them in mind when purchasing gas mask filters.
And beyond the primary classifications, there are a few more profound points to consider…
First is the level of particulate-filtering efficiency. This is a crucial consideration. After all, it's not just about the contaminants in case of a disaster—there will also be a great deal of dust and airborne debris. These particles can gradually accumulate inside the filter itself, reducing efficiency and increasing your chances of exposure.
Particle filter levels are currently defined by the EN143 standard to protect users against airborne dust, particles, and liquid/solid aerosols. P1 level filters are less efficient, designed to stop at least 80% of airborne particles. P2 filters are designed to block 94% of airborne particles, and P3 filters offer high efficiency, cutting off at least 99.95% of all airborne contaminants (all at 95 L/min airflow).
Particulate filtration is critical to surviving many CBRN threats, which is why most current CBRN filters offer P3 protection.
Another major factor to consider is the "reactor" classification. As mentioned above, this classification indicates the filter can prevent the intrusion of radioactive iodine often associated with nuclear fallout or post-meltdown exposure. Genuine CBRN filters should almost always have this designation.
Filters may be labeled as either NBC filters (nuclear, biological, chemical) or CBRN filters (chemical, biological, radiological, nuclear). The former is generally considered an outdated term from the Cold War. Some of the most common NBC filters on the market today are old Israeli civilian filters which you're best off avoiding.
In recent years, NBC filters evolved into CBRN to provide protection from radiological threats like dirty bombs, so you're best off going for CBRN filters when possible.
Filter Certification
Of course, a filter's classification is only as good as the agency that certifies it—and the standards to which it's certified.
As mentioned above, the National Institute for Occupational Safety & Health (NIOSH) is a certification body for American masks and filters. However, NIOSH certification can be prohibitively expensive for smaller companies, so it typically comes at a premium cost to the consumer.
It's important to note that NIOSH CBRN certification is given to the mask and filter as a unit. So switching to a different filter or a newer mask may sometimes be a step away from the NIOSH standard.
And that's the key with NIOSH; it's an optional certification unless your mask is part of your occupational equipment. You can get a great non-NIOSH mask and filter.
Europe's "CE" is an equally strict standard, and the difference is that while non-NIOSH masks can be sold in the US, non-CE masks cannot be sold anywhere in the European Union.
As we've covered above, GOST is a Russian standard that closely mirrors CE.
GOST also has its own threading standard, so if you are considering GOST-approved filters, ensure they're compatible with your gas mask.
But what's the right filter for your needs?
If you're in the private sector, you'll likely need a more expensive NIOSH-approved setup (more on that in a moment).
State and federal jobs aren't regulated by NIOSH standards, which gives you more options. Instead, if you're just trying to prepare for the worst, you can get reliable NATO standard masks and filters for a lower price. Preparing for specific use cases can make your purchases more effective.
But first and foremost, you need to know what you're purchasing. So let's take a look at how filters are classified and defined.
Top 3 Gas Mask Filters of 2023
While your individual needs may vary, just a few filters are perfect for most civilian or professional buyers as they cover the most comprehensive array of threats.
No gas mask filter can do it all, but these top choices come as close as anything out there. They're each best in class, proven performers with stellar reviews from consumers and experts alike—so you can confidently buy any of these popular filters.
And, of course, we know which filter takes the top spot…
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Awesome 20-year shelf life
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Wide range of protective filtering
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Level P3 particle filtering
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Reactor element
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Vacuum-wrapped for easy storage
It may sound biased, but we take pride in what we do.
MIRA Safety's filters culminate decades of specialized expertise and manufacturing, creating some of Europe's best gas mask filters.
Each filter comes individually packaged in its own vacuum-sealed pouch, with clearly-labeled expiration dates and comprehensive protection from a wide variety of airborne compounds.
These filters come with an unmatched 20-year shelf life that can make storage and logistics incredibly easy.
Certified according to some of the strictest European standards, our NBC-77 SOF filters take much of the guesswork and research out of buying gas mask filters by giving you an obvious first choice for most practical uses.
But every respirator filter has its limitations…
For the NBC-77 SOF, the initial price is higher than other filters. Of course, that pays off in the long run, with a shelf life up to four times longer than many filters.
Combining the best value with the best protection and storage-ready packaging, these are the best all-around filters to suit most buyers. If you don't read another word, immediately buy some NBC-77 SOF filters for yourself and your family.
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Incredible value
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Full-spectrum protection
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Lightweight polymer housing
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7.5-year shelf life
When buying gas mask filters, our first and most important advice is to "buy as many as you can comfortably afford," The DOTPro 320 is easily the most affordable filter on the market today.
It's got great features, Level 3 particulate filtering, and stats that match top filters in the quality of the numbers. But it also combines a 7.5-year shelf life with a price that beats the competition by about 20%. As a result, the DOTPro 320 is just an easier purchase to make. When you're buying 10, 20, or 30 filters or more, those savings really add up.
And it's important to reiterate that you're sacrificing only a little in terms of protection with the DOTPro 320. To be sure, there's no reactor element, and it's not NIOSH-approved. But aside from those omissions, you're getting the same quality and peace of mind you'd get from a filter like the NBC-77 SOF at about half the price.
Regarding budget-friendly gas mask filters, look no further than the DOTPro 320 for maximum value.
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Ultra-compact
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Lightweight
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Made using ULPA filtration technology
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Rated to stop 99.9995%+ of viral and biological particles
In some cases, you'll only need protection from biological threats (viruses, bacteria) or inhaled particulate, making our P3 filter the optimum choice.
P3 filters come in packs of six, with the same 20-year shelf life as our NBC-77 SOF gas mask filters. Unlike those filters, the ParticleMax only has P3 certification. That's the highest level of protection you can get from inhaled particulate, but it won't be sufficient protection from chemical weapons or nuclear fallout.
These filters are your top choice in the event of a pandemic, and they're also great for training.
Filter Storage & Shelf Life
The best gas mask filter is, of course, the one you never need to use.
But if the need arises, you want to be sure you can count on your gear—so we'll take a moment to cover the storage, shelf life, and logistics.
It is vital to focus on logistics when purchasing, storing, and maintaining gas mask filters. You will want between 7-20 filters for each family member or group, and the filters have an average shelf life of 5-10 years. Successfully managing and storing that amount of sensitive equipment can require some clever thinking.
Take, for example, our MIRA Safety CBRN NBC-77 SOF Gas Mask Filter. This filter sells at a substantially higher cost than a lot of the competition, so a price-minded buyer might steer clear of it. But if you're focusing on logistics, you'll notice that the NBC-77 SOF filter lasts 20 years on the shelf—four times the effective lifespan of most filters. That feature can massively simplify your logistics and maximize value, so taking the right approach is essential.
When it comes to storage, a general rule of thumb is to store your gas mask filters like you would store ammunition or anything else you consider valuable. So, keep filters away from temperature extremes and sunlight, and store them at less than 80% humidity.
Some CBRN filters come pre-packaged in a vacuum-sealed bag, minimizing the need for handling and the risk of moisture. It goes without saying that filters should be kept in these bags, and indeed, you should consider bagging your own filters if you have a vacuum sealing machine at home (just be careful not to put too much pressure on the housing).
Once your filters are properly stored, you're good to go for years.
Just monitor environmental conditions, and track any new purchases/additions so you can keep an eye on expiration dates. Modern NATO filters will have expiration dates clearly printed out on the outside of the canister, so you can keep track of shelf life as time passes.
It goes without saying that you should NOT renew your filters by blasting them with compressed air or attempting to wash them. Instead, safely dispose of the filter once it's expired and replace it as soon as feasible.
Filters to Avoid
As you've already discovered, finding the right gas mask filter is crucial. But it's even more critical to avoid the wrong gas mask filters…
It all starts when governments buy filters in bulk. They stockpile millions, preparing for a catastrophe that hopefully never comes. When the gas mask filters ultimately expire, a contractor is hired to dispose of them safely and effectively.
Instead, these often useless and sometimes dangerous filters don't make it to landfills. The filters show up on eBay and are purchased by unwitting consumers.
This has become a real problem in Russia, Israel, and the Czech Republic.
Russian GP-5/GOST “Asbestos Filters”
These are the most notorious gas mask filters online since the GP-5 was a popular surplus choice for years. Some older versions of these filters contained asbestos, which was phased out long before any of today's viable filters were made.
Nonetheless, these filters can still contain chemicals/carcinogenic compounds that have recently been found to be dangerous. It's best to avoid the aging GP-5 and its filters altogether. Production of the mask ended all the way back in 1990, so it's practically impossible to find a GP-5 mask worth trusting on the market today.
Israeli Surplus Filters (M15 & Civilian)
Israeli masks and filters are honestly not bad.
They need to be updated regarding design and features, but they still do the job. So why avoid them? Because the Israeli masks you'll find here in the United States just aren't consistent enough to trust with your life.
Expired filters, compromised masks, and various other problems plague these typical, budget-friendly masks. So, unfortunately, despite their solid track record, we have to recommend staying away from Israeli Surplus masks & filters.
Mystery Filters
This is a catch-all for any filter that's improperly labeled, lacks a legible expiration date, or is in any other way suspicious. If you're not confident that you know precisely what the filter is for and when it was made, it's best not to trust it with your life.
That includes any filter that comes with an outdated gas mask, like any of the following:
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GP-5 gas mask
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Czech M10 gas mask
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Canadian C-4 protective mask
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Serbian M1 gas mask
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M17 gas mask
If it's a matter of translation or identifying a foreign filter, you may find clues among online forums, but be careful to double-check and confirm anything you read.
Finding Good Filters Is Getting Easier
In the past, when there was less of a market for gas masks and filters, it was common to see low-quality surplus online or at gun shows.
Fortunately, avoiding these types of filters is getting easier as the market is becoming increasingly sophisticated. If it's feasible for you and your budget, it's best to avoid all but the very best gas mask filters.
We're talking about the very air you will breathe in the event of a major disaster. If and when your life is at stake, you won't care whether you saved a few extra bucks on a gas mask filter, so make sure to buy something that gives you peace of mind. Especially when some premium filters last up to 20 years on the shelf.
Buy once. Cry once. And avoid cheap surplus gas mask filters like the plague.
Conclusion
Buying and storing suitable gas mask filters for your personal needs is a potentially life-saving decision that only takes a few minutes.
As you've discovered so far today, there are a great many factors that determine what each filter is useful for, how much it costs, and how long it lasts. It may initially seem overwhelming, but your needs (and choices) will be pretty straightforward.
All it takes is a few good CBRN filters from a trusted vendor, and you're stocked up for years. So it's easy to take an extra moment and ensure you know what you're getting.
If your budget is limited, you have a few ideas for filters that will work without breaking the bank. The upcoming VK-530 is an excellent way to add versatility to your gas mask setup. And if you need a NIOSH-approved filter for work, then the RD40 is what you want.
Whether you're facing wildfires or a nuclear meltdown, riot control measures, or an explosion at a chemical plant, there's a gas mask filter designed to help you get the job done and get to safety.
Be prepared—and stay safe.
Gas Mask Filter FAQ
Gas mask filters combine a layer of mechanical filtering with chemical filtering—separating different particles, bacteria, and airborne contaminants through adsorption, where toxins adhere to elements inside the canister filter. Space inside the filter is limited, and these filtering mechanisms are complicated/delicate, so filters are often specialized and priced based on how sophisticated the internal elements are.
NOTE: Gas masks and gas mask filters ONLY protect your respiratory system from airborne contaminants. If you're not wearing a hazmat suit appropriately sealed with ChemTape, gloves, and boots, your body could still be exposed to potentially dangerous elements.