Gas Mask Filters: How To Choose The Best 40mm Mask Filter

A gas mask is only as effective as the filter it uses

Choosing the right gas mask filter is just as important as choosing the right gas mask, if not more. The reason is, without doing the right research, you run the risk of getting a gas mask filter that either does not fit the gas mask you have invested in, or does not filter and create clean, breathable air in an NBC/CBRN environment. Understanding how to choose the right filter, and ensuring that you have the right filter suited to your environment will help you make the right informed decision about getting the right gas mask filter for what your gas mask.

In this post, we will take a look at the three most important things to know so that you can choose the right gas mask filter. We also look at the four best NBC/CBRN filters and how to choose a filter, and some commonly asked questions. So let’s get started.

3 Things To Remember About Gas Mask Filters

There are three very important characteristics to remember to get the right gas mask filter for what you need.

First, filters can differ in which mask they fit. For most gas masks, they are made with threading that will fit a 40mm gas mask filter, which is also referred to as the NATO 40mm standard. This is the type of filter that is both very readily available in stock, and the one your neighbor is likely to have in stock, if any.

Second, ensure that you are able to use the filter in the right environment or scenario, most new filters that have been manufactured in the past 5-10 years come with an NBC rating (Nuclear, Biological, Chemical) as well as a CBA-RCA rating. This means that they are made to filter nuclear, biological or chemical substances in the air that would otherwise cause harm to the body. A CBA-RCA rating stands for Chemical Biological Agent-Riot Control Agent. In that circumstance, it would not filter radiation, but would withstand any specific hazardous chemical experienced in general policing and law enforcement environments.

Third, is the timing in which the gas mask filter lasts before it needs changing to a new filter, (eight hours is the standard for most). The timing also applies to the gas mask filter’s expiry date. All filters are made with visible expiry dates which must be adhered to in order to ensure you get the right filtration for your gas mask.

To ensure you are getting the right gas mask filter, there is a color code system on all gas mask filters to identify what they are capable of filtering. The table below identifies the colors you may see on a gas mask filter.

Gas mask filter color code chart

Gas mask filter colors

Now that we know how to effectively choose a gas mask filter that is suited to what environment we can expect, let’s take a look at four of the best and most popular NBC/CBRN filters that are avaialable.

The Four Best Gas Mask Filters

Mestel 40mm CBRN Gas Mask FilterCBRNNATO 40mm
Draeger Rd40CBRN 40mm NATO filterCBRNNATO 40mm
Israeli NATO40mm NBCfilterNBCNATO 40mm
Avon M50 CBRN GasMask filterCBRNAvon M50

1. Mestel Safety 40mm CBRN Gas Mask Filter

gas mask filter canisters

The Mestel Safety 40mm NATO CBRN filter protects against all known biological and chemical agents and is tested against chemical warfare gases and toxins. The particulate filter is 99.99% efficient against particles and has a high protection against any aerosols. It comes with a five-year shelf life and has a 40mm NATO standard threading.

More specifically, this Mestel gas mask filter is able to filter chemical and biological toxins such as sarin gas and other nerve gases; mustard, arsine; radioactive and toxic particles; aerosols and micro-organisms; bacteria and viruses. It also protects against industrial gases (type A2B2E2), organic gases and vapors, inorganic gases and vapors, e.g. chlorine, hydrogen cyanide, hydrogen sulfide, organic and inorganic acids, such as formic acid, sulfur dioxide, hydrogen fluoride and hydrogen chloride. Warfare and terrorism agents such as anthrax, sarin, smallpox, mustard gas as well as riot control agents like CN and CS tear gases.

This filter comes with a 5-year shelf life.

2. Draeger 40mm CBRN Gas Mask Filter

gas mask filter reviews

Draeger’s 40mm NATO CBRN filter is a high-quality gas mask attachment filter that protects against all known biological and chemical agents. It is a filter offering users protection against a wide range of hazardous gases and vapors and is 99.95% efficient in filtering out dust and particulates.

This filter comes with a shelf life of 6 years from the date of its production. It is CE approved (EN 141:2000 re. EN 14387, EN 143:2000, EN 371) and SAI Global-approved (Australia).

3. Israeli Manufactured NBC Filter

Israeli gas mask filter

The Israeli NATO 40mm NBC gas mask filters were developed for the Israel Defense Force (IDF) and Israeli citizens to provide protection against all known NBC agents in the form of vapors and aerosols. This is generally combined with the Israeli gas mask which was manufactured for civilian use against chemical and nuclear attacks

The Type 80 gas mask filter is a robust durable canister intended for military and civil defense use. It is specially designed for comfort and extended use at a minimal physiological load, having low breathing resistance and low weight. Its design assures optimal performance complying with all IDF specifications as well as the performance requirements of the American Army C2 filter canister. The filter is supplied with a standard Nato thread (40 mm x 1/7”) and is compatible with almost all military and industrial respirators. The Type 80 filters are supplied sealed with leak-proof plastic caps, assuring a shelf life exceeding 15 years.

4. Avon M61 Filter (For Avon M50 US Military Mask)

NBC gas mask filter

The M61 gas mask filters are specifically designed for the US Military and UK Defense standard Avon M50 gas mask. They do not meet 40mm NATO threading standards so cannot fit any other gas mask except for these specific gas masks. However, they are a high-quality filter that provides up to 24 hours of gas mask filter protection from chemical and biological agents and radioactive particles.

These filters are designed as a twin filter system that sits close to the face, providing high protection and very low breathing resistance which suits there military use in demanding physical environments. They protect against chemical, biological, radiological, and nuclear (CBRN) threats (including toxic industrial materials).

More specifically, they are suitable against:
Arsine, Asbestos, Bacteria, Benzene, Blister Agent, Blood Agent, Bromine, Carbon Dioxide, Carbon Monoxide
Carbon Tetrachloride, Chlorine, Chlorine Dioxide, Chloroacetophenone (CN),Chloropicrin, o-Chlorobenzylidene Malononitrile (CS), Cyanogen, Cyanogen Chloride (CK), Cyclohexane, Fluorine, Formaldehyde, Hydrogen Chloride, Hydrogen Cyanide (AC)
Hydrogen Sulfide, Lewisite, Mustard (HD), Nerve Agent, Nitrogen Dioxide, Nuisance Dusts, Nuisance Odors, Oleoresin Capsicum (OC, Pepper Gas), Organic Vapors w/ Boiling Point >65 Degree C, Particulates, Phosgene, Phosphine,Radioactive Particulates, Sarin (GB), Soman (GD) Sulfur Dioxide, Tabun (GA), Toluene, Virus, VX, Xylene.

The M61 filters have a predicted shelf-life of 5 years (when sealed and packaged).

You might be interested to know what type of gas mask Navy SEALs use.

How To Choose A Gas Mask Filter

What is the purpose of the gas mask filter?

Gas mask filters are catered to cover a variety of purposes, whether it be for military, law enforcement, or for industrial chemicals such as aerosols and asbestos. The essential purpose of a gas mask filter is to ensure that it stops hazardous particles from entering the airways and causing risk to the body, the process of gas mask filters are what makes them different in their operation and capacity to filter certain particles and gases.

Taking a look at the image below shows how a gas mask filters particles, gases, and toxins from the contaminated air, making it safe to breathe. Most top quality NBC and CBRN gas masks use charcoal filters as a way to effectively ‘catch’ particles as they float through the air when a breath is drawn into the gas mask.

A military-grade filter (NBC/CBRN) will work in two ways. First, it does a simple particle filter, much like a water filter would, and removes the bacteria in the inhaled oxygen. This is essentially a physical barrier, acting like a cloth being held over your mouth to stop smoke inhalation, only this one covers much finer particles. The next process is adsorption and is a chemical process, unlike the first one, to remove toxic gases and molecules. This is where gas masks differ to things such as respirators, dust masks, or using a wet cloth over the mouth while escaping a burning building. The respirator and damp cloth would trap particles, but would not filter toxic gases.

How a gas mask filter works


What type of gas mask filters are there?

There are a number of gas mask filter types out there, depending on the circumstances of the environment you are working in. Of course, when it comes to environments where particles of a nuclear, biological or chemical nature appear (NBC/CBRN) then the appropriate gas mask filter would be a combination of factors.

For riot police, gas mask filters would use primarily organic compound filters, whereas industrial areas would generally stock gas mask filters that focus on trade-specific hazards such as inorganic gases and vapors or sulfur dioxide and hydrogen chloride.

Types of gas mask filters

How long do gas mask filters last for?

There are two important things to take note of when you purchase your first gas mask filter, that is the expiry date and the duration time that it can provide clean filtered air. The expiry date will often indicate the shelf-life, or how long it lasts after it was manufactured. This is important to note as gas mask filters can vary from two years to five or 10 years, depending on the compounds in the gas mask filter and the specific material it filters.

The other important thing to know is how long the gas mask filter can actually provide pure filtration for in a hazardous situation. This information will be indicated on the packet of purchase so pay attention to the box and insert you get when you first open the gas mask canister’s packaging.

In a nuclear, biological or chemical situation (NBC/CBRN) most gas mask filters will last between 12 -24 hours. This depends on the concentration of the hazardous material that the gas mask filter is filtering. If it is a closed environment with thick toxic gases, the gas mask filter might only last for up to an hour.

How will I know when to change my gas mask filter?

First, you should always keep an eye on the shelf life of your gas mask filter and ensure that it is within date at all times. Regular check-ups on the shelf life and validity of your filter will ensure that you can actually use it when you need it the most.

During a hazardous event, when your gas mask filter is filtering hazardous substances, you will notice when it is nearing time to change the filter as the breath will be hard to draw through. As time goes on, you will slowly begin to notice that breathing will become more and more restricted through the filter.

Our thoughts on the best gas mask filter

It is quite a common question to ask: “which gas mask filter should I get?”. this entirely depends upon the use of your gas mask and what you are preparing for. Uses can vary from police and law enforcement work, firefighters with smoke, military use, journalists covering street riots and protests, to industrial work.

Once you have identified where you will be predominantly using your gas mask, identify the colors on the filter scale that match with the likely hazards in your area. As a safe bet, if you have purchased an NBC/CBRN gas mask, to ensure it is able to filter NBC or CBRN substances, acquire the appropriate filter for that purpose.

Gas Mask Filter Frequently Asked Questions

Having been an active member in many survival and prepping forums, I have always enjoyed answering a few different questions on gas masks, respirators and filters. Here are some of the common questions I get asked.

How long does a gas mask filter last?

Most gas mask filters will last for around 24 hours in an NBC/CBRN situation. When the breathing starts to become restricted it is time to change the filter on your gas mask.

What is the shelf life of a gas mask filter?

The shelf life of most NATO 40mm gas mask filters ranges from 5-15 years. The manufacture date and the shelf life date will be printed on the packaging that they come in.
More specifically, the Israeli 40mm NATO gas mask filter has a shelf life exceeding 15 years, whereas the Avon M50 gas mask filters have a shelf life of five years.

How do I know if my gas mask filter will fit my gas mask?

Gas mask filters can vary in threading. However, the best way to make sure that you have the right filter for your gas mask is to check on the packaging that it comes in. This is also sometimes displayed on the filter attachment on the gas mask.

If in doubt, ensure that you check your packaging and check with the manufacturer. If you are concerned about having the right fitting gas mask filter, or you are concerned about ensuring that you have a steady supply of filters, a safe bet is to ensure that you get a gas mask that fits a 40mm NATO filter, as this is the most common type of filter available on the market and will most likely be the filter that your neighbour, emergency professionals, and stores, will have.

Over to you…

Choosing the best NBC/CBRN gas mask filter is choosing the mask that does what it needs to during its intended use ultimately keeping you safe. With that in mind, the above points should help in determining and narrowing down the best gas mask filter for you.

choosing a gas mask filter

2 thoughts on “Gas Mask Filters: How To Choose The Best 40mm Mask Filter”

  1. Just a tip on the Israeli filters for some buyers, when you get the Israeli mask, they do come with filters but they might be expired, so it’s best off you buy a new one.

  2. I am a citizen preper and I have a mask and i have several filters my concern is trying to figure out which one to use in a “toxic train accident” or other random event.


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