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Gas Mask Filter Buyer's Guide

We can survive three weeks without food and three days without waterbut only three minutes without breathable air.

That's why gas masks can be a lifesaver in case of disasters like terrorist attacks or nuclear meltdown. But you might not realize that without the right filter, even the best gas mask is useless.

Because modern 40 mm gas mask filters are specialized to deal with any number of hundreds of toxins and airborne contaminants-ranging from chemical to bilogical, radiological and even nuclear-all while fitting the same gas mask.

A single filter can protect you from all of the contamination from a nuclear meltdown for forty full 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 how to impregnate 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 even experienced buyers. That’s a mistake that can cost you time and money…or something even more important.

So, we’re going to 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 potentially 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

  • 01

    Gas Mask Filters 101

  • 02

    Filter Classification

  • 03

    Filter Certification

  • 04

    Top 4 Gas Mask Filters of 2020

  • 05

    Filter Storage & Shelf Life

  • 06

    Filters to Avoid

  • 07

    Conclusion

  • 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.

Modern gas mask filters, on the other hand, are truly 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 the science, it takes a great deal of craftsmanship and knowledge to do it correctly. This special 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, micro-organisms, and highly toxic particles. Particle, combined, special and NBC filters are equipped with special hydrophobic P3 class filter elements to ensure superior performance.

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Gas Mask Filter Function Basics

Gas mask filters rely on three chemical processes to provide clean air in even the most toxic environments.

Filtration

is the most basic process, separating solid particles and aerosols from breathable air using media like charcoal.

Physical adsorption

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

happens when physical adsorption meets the impregnated chemicals in a filter's activated carbon. During this process, even the most toxic elements can be momentarily captured, 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

use basic filter media like Class 16 fiber paper to filter out common toxins. They're basic and affordable due to their simple construction. These are more often used for construction and demolition.

2. Gas filters

use the impregnated carbon we talked about above 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

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

like most CBRN filters on the market today, take protection to an even higher level, with safeguards against things like organic substances with low boiling points, including mercury, COx, NOx and radioactive metal iodide.

To produce a modern gas mask filter takes unprecedented 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, and depending on the specific filter, they can provide up to 40 or more hours of practical protection from airborne contaminants and toxins. Any worthwhile gas mask filter will have these details laid out in the included documentation. This can make logistics straightforward, as you’ll see 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 that’s associated with a raft of 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-450 can be GOST-certified while using the standard NATO 40mm threading, giving you a practical and budget-friendly alternative that still 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 just important to steer clear of expired GOST filters or anything from the 80s and 90s. These older filters can contain chromium or asbestos, both of which can be seriously hazardous.

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 it can also limit your choice of filters—at a higher cost than civilian-ready CBRN masks and filters.

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Key things to remember about gas mask filters

  • Gas masks & filters require at least 17% ambient oxygen levels (19.5% if in accordance with NIOSH) to function, any less requires a self-contained breathing apparatus (SCBA).

  • 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.

  • 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 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!

  • Always use a filter with the P3 or P3D filter element against solid and liquid particles, micro-organisms, viruses, smoke, etc.

  • The maximum useful life of a filter against mercury vapors is legislatively defined by European standards as 50 hours.

  • Gas mask filters cannot be cleaned so do not apply pressurized air or water.


As you can already see, there’s no shortage of choices when it comes to picking your mask and filter. If you feel overwhelmed, it can be helpful to take a step back and ask what you really 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, weight and being porous enough for you to comfortably breathe through them.

That’s why individual filters are classified and coded according to a strict system, informing users of the specific types of toxins and compounds each filter can protect against.

Color Mask type Application Class Gas Concentration Standard
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
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 important to keep them in mind when purchasing gas mask filters.

And beyond the basic classifications, there are a few deeper 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’s also going to be a great deal of dust and airborne debris. These particles can gradually accumulate inside the filter itself, reducing efficiency and increasing the chances you’ll be exposed.

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 stop 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 key to surviving many CBRN threats, which is why most modern 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. True 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 key certification body for American masks and filters. NIOSH certification can be prohibitively expensive for smaller companies though, so it typically comes at a premium in terms of cost to you, 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 in some cases 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. 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, make sure they’re compatible with your gas mask.

But what’s the right filter for your needs?



If so, and 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 it is that you’re purchasing. So let’s take a look at how filters are classified and defined.

Top 4 Gas Mask Filters in 2020

While your individual needs may vary, there are still just a handful of filters that are perfect choices for most buyers, whether civilian or professional, as they cover the widest array of threats.

No gas mask filter can do it all, of course, 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 buy any of these popular filters with confidence.

And, of course, we know which filter takes the top spot…

  • Awesome 20-year shelf life

  • Wide range of protective filtering

  • Level P3 particle filtering

  • Reactor element

  • Vacuum-wrapped for easy storage

It may sound biased, but we take pride in what we do.

MIRA Safety’s filters are the culmination of decades of specialized expertise and manufacturing, creating some of the very best gas mask filters that Europe has to offer.

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 some of the best protection and storage-ready packaging, these are easily the best all-around filters to suit the vast majority of buyers. If you don’t read another word, buy some NBC-77 SOF filters for yourself and your family immediately.

  • Turns your gas mask into a smoke escape respirator

  • Offers full-spectrum CBRN protection

  • Ideal protection for home fires & wildfires

  • Functional in low oxygen environments

  • 13.5-year shelf life

  • 13Expensive

No other gas mask filter demonstrates the flexibility of the platform quite like the VK-450. In a matter of seconds, the VK-450 can transform a standard gas mask into a fully functional smoke mask.

Utilizing special media and a high-grade particle filter, the VK-450 is able to retain a wide range of CBRN protection while adding practical protection from smoke, carbon monoxide and airborne particulates.

That added functionality can move your expensive gas mask from the closet to the bedside—transforming it into a potentially life-saving tool in case of smoke exposure. If you’re stocking up on filters, the VK-450 seems like an obvious buy.

The downsides are limited but noticeable.

First, the filter lacks a reactor certification. That means no protection from radioactive iodine in case of nuclear fallout. Assuming you’ve got another filter that’s reactor-certified for full CBRN exposure (like the NBC-77 SOF) then that’s not much of an issue.

But every respirator filter has its limitations…

Likewise with the filter’s higher price. Since you’re only likely to need one or two of these filters, the higher price tag is easier to reconcile. They’re also slightly larger than most filters, which is a minimal inconvenience.

  • Incredible value

  • Full-spectrum protection

  • Lightweight polymer housing

  • 7.5-year shelf life

When it comes to buying gas mask filters, our first and most important piece of advice is to “buy as many as you can comfortably afford,” and the DOTPro 320 is easily the most affordable CBRN filter on the market today.

It’s got great features, Level 3 particulate filtering and stats that match top filters in by the numbers quality. 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, 30 filters or more, those savings really start to add up.

And it’s important to reiterate that you’re not really sacrificing all that much in terms of protection with the DOTPro 320. There’s no reactor element, to be sure, 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.

When it comes to budget-friendly gas mask filters, look no further than the DOTPro 320 for maximum value.

  • Ultra-compact

  • Lightweight

  • CBRN effective

  • Military proven

  • Expensive and impossible to find

The biggest innovation with the U.S. military’s new Avon M50 is to split the standard single filter into two smaller filters. This allows each filter to sit closer to the face, with dual ports to reduce breathing resistance and a compact form factor that allows for easy maneuvering and rifle handling.

Of course, there are a few downsides. First, the shelf life is limited at 5 years. Second, they only last 24 hours at best due to limited filter capacity. And third, they’re practically unavailable in any reliable form to civilian and non-military buyers. While you might find an M50 mask or filters online here and there, you won’t be buying them from a reliable dealer, so you shouldn’t trust your life to them.

Nonetheless, the M50 is a tremendous innovation that deserves some credit.

Filter Storage & Shelf Life

The very best gas mask filter is, of course, the one you never need to use.

But if the need arises, you want to be absolutely certain you can count on your gear—which is why we’re going to take a moment to cover storage, shelf life and logistics in general.

It really is key to focus on logistics when purchasing, storing and maintaining gas mask filters. You’re going to want between 7-20 filters for each member of your family or group, and the filters having 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 a whopping 20 years on the shelf—four times the effective lifespan of most filters. That kind of feature can massively simplify your logistics and maximize value, so it’s important to take the right approach.

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 might want to 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 the outside of the canister, so you can keep track of shelf life as time goes by.

It hopefully goes without saying that you should NOT try to 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, it’s important to find the right gas mask filter. But it’s even more important to steer clear of 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 the landfill. They show up on eBay, and are purchased by unwitting consumers.

This has become a very real problem in countries like Russia, Israel and the Czech Republic.



Russian GP-5/GOST “Asbestos Filters”

These are probably 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 probably 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’re a bit outdated in terms of design and features, but they still get the job done. So why avoid them? Because the Israeli masks you’re going to find here in the United States just aren’t consistent enough to trust with your life.

Expired filters, compromised masks and a variety of other problems plague these common, 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 exactly 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:

  • GP-5 gas mask

  • Czech M10 gas mask

  • Canadian C-4 protective mask

  • Serbian M1 gas mask

  • 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, it’s getting easier to avoid these types of filters as the market is becoming more and more sophisticated. If it’s feasible for you and your budget, it’s honestly 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’re not going to 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 for 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 the right 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 might seem overwhelming at first, but for the most part, your needs (and your choices) are going to be pretty straightforward.



All it takes is a few good CBRN filters from a trusted vendor, and you’re stocked up for years to come. So it’s easy to take an extra moment and ensure that you know what you’re getting.

If your budget is limited, you’ve got a few ideas for filters that will work without breaking the bank. The VK-450 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 FAQs

Here are some final FAQs that you might find helpful when choosing a gas mask:

How exactly does a gas mask filter work?

Gas mask filters combine a layer of mechanical filtering with chemical filtering—separating different particles, bacteria and airborne contaminants through processes like 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 that’s properly sealed with ChemTape, gloves and boots, then your body could still be exposed to potentially dangerous elements.

How long does a gas mask filter last?
How do I know when to change the filter?
How do I know I can trust the gas mask filter manufacturer’s claims?
How many gas mask filters do I need?
Are gas mask filters reusable?
How do I dispose of expired/damaged filters?
Are surplus filters safe?
Can I use an adapter to use NATO filters with GOST masks?

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