Best 40mm Gas Mask Filters Guide by Parcil Safety

Parcil safety 40mm filter canister options

In the respiratory protection industry, it can be difficult to determine what type of filter to go with. You have different filter attachment types, different chemical filtering capabilities, and different filtration ratings. There are three main filter attachment types – 40mm, industry standard bayonet, and manufacturer’s proprietary filter attachments. Proprietary filter attachments include using a threaded, snap-in, or push-to-connect design.

Today, we will be just focusing on the 40mm filters.

If you’re looking to protect you and your family in an emergency situation, biological or chemical attack, or in a survivalist or prepping situation, then you will most likely be looking for a gas mask that takes NATO 40mm threaded filters. One potential situation may be WW3 (check out our guide to surviving WW3 here).

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What is a 40mm Filter Canister?

In general, 40mm gas mask filters are protective filters that are designed to be used with gas masks and refers to the standard size of the filter threading, which allows the filter to be used with any gas mask that has 40mm filter threads. These filters are typically made of activated carbon, which is a form of carbon that has been treated to be highly porous and able to absorb chemical compounds. The activated carbon in the filter works to adsorb (not absorb) harmful chemical gases and particulates from the air, making it safer to breathe.

Is there a difference between NATO 40mm and a standard 40mm Canister?

NATO 40mm filters are protective filters that are designed to be used with gas masks and respirators that have 40mm filter threads, but they are also designed to meet the performance requirements of the North Atlantic Treaty Organization (NATO), which is a military alliance of 30 countries from Europe and North America. These filters are typically used by military and law enforcement personnel to protect against a variety of hazardous substances, including chemical gases and particulates. NATO 40mm filters are often used in conjunction with other protective equipment, such as gas masks and protective suits, to provide a high level of protection against a wide range of hazards. CBRN, NBC or CBA-RCA rated filters are also typically NATO 40mm. Read the differences between CBRN, NBC or CBA-RCA in our explainer article.

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There are several common type of 40mm respirator filters, including:

  1. Particulate filters: Particulate filters are designed to remove solid particles from the air, such as dust and dirt. They are typically classified according to their ability to filter out particulates, with classifications ranging from N95 (95% efficiency) to N100 (99.97% efficiency) or P1 (80% filtration) to P3 (99.9%).
  2. Gas and vapor filters: Gas and vapor filters are designed to remove specific gases and vapors from the air. These filters are typically classified according to the types of gases and vapors that they can remove, as well as their capacity for absorbing these substances.
  3. Combination filters: Combination filters are designed to remove both particulates and gases/vapors from the air. These filters typically have a particulate filter on one side and a gas and vapor filter on the other side, and are used when both types of protection are needed.

The most common rating systems are governed by the US (NIOSH) and European Standard (EN / CE).

Parcil Safety is currently testing to the EN / CE standards, so we will focus on that one for our 40mm filters.

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Some general guidelines on when selecting a 40mm gas filter

When you select a 40mm filter (one that filters out the chemical or particulate you are needing protection from), you need to make sure it filters out high enough concentrates for the job or situation you may be in, and you need to know how long they last – both the shelf life for emergency use and duration of the canister.

A2 B1 E1 K2 P3… What does it all mean?

For CE certified gas masks and filters, there are 2 main components to determining which filter is right for you (visit for more information on NIOSH CBRN):

  • The Chemical Filtered Rating – This is the letter designation and color-coded rating on the filter canister. They include P rating for particulate, A for organic vapors (boiling points that are > than 65 degrees Celsius), B for inorganic vapors, E for acidic gases, K for ammonia, HG for mercury, NO for nitrogen oxides, AX for organic vapors with boiling points less than 65* Celsius, and SX for specialty filters. We’ve put all the information and the color code in a small chart below:

40mm Gas Filters Color Coding Chart for Parcil Safety

  • The Concentration Rating –the concentration rating typically follows the letter designation for chemical filter rating, and is either a 1, 2 or 3 (for CE / EU standards). Below we will use organic (A), inorganic (B) and acidic gas (E) as examples:
  1. A1 / B1 / E1 / K1 = low capacity and rated for max concentration levels of 1,000 ppm.
  2. A2 / B2 / E2 / K2 = medium capacity and rated for max concentration levels of 5,000 ppm.
  3. A3 / B3 / E3 / K3 = high capacity and rated for max concentration levels of 10,000 ppm.

So, let’s wrap it all together – a filter with an ABEK1P3 rating would filter organic, inorganic, acidic, and ammonia vapor and gases with a max concentration level of 1,000 ppm and protection again 99.9% of airborne particulates.

Parcil Safety 40mm Filter Guide

Now that you know a little bit more about 40mm filters, next we want to talk about the 40mm filter options that Parcil Safety has to offer.  Starting from lowest level of protection going to the highest.  If you are looking for more industrial or half face respirators, check out that guide HERE!

All our 40mm filters are compatible with the following Parcil Safety gas mask offerings:

Parcil Safety's 40mm Gas Masks Offering

Best 40mm Filter for Particulate ONLY Filtration 

 ParticulatePro P3R 40mm Gas Mask Filter Canister.


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The ParticulatePro P3R is a great filter if you are looking to filter out 99% of airborne particulates ONLY. Common applications would include filtration against dust, asbestos, smoke or other particulate based irritants.

Particulate Pro Technical Filter Specs

Best 40mm Filter for Low Concentrate Organic Vapors and Airborne Particulate Filtration

 P-D-1 Organic Vapor Filter Canister

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The P-D-1 Organic Vapor Filter Canister is a dual combination A2P2 40mm filter that comes stock on our ST-100X gas mask model. This is great when you are looking for protection against low concentrates of organic vapors or particulates. Common chemical filters include wood shavings, concrete dust, smoke, non-oil based paints, tear gas, and pepper spray.

P-D-1 Organic Vapor Spec Sheet

Best 40mm Filter for High Concentrate Organic Vapors and Airborne Particulate Filtration

 OrganicPro N-B-0 Filter Canister

N-B-0 OrganicPro 40mm Filter Canister

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The OrganicPro N-B-0 Filter Canister is our option for those looking to filter out high concentrates of Organic Vapors and Airborne particulates.  The N-B-0 features an A2P3 R filtration rating, meaning it can filter down to 99.9% of airborne particulates.  It filters out similar chemicals and particulates to the P-D-1, but it also is great for asbestos or black mold filtration due it's P3 particulate rating.   

N-B-0 Organic Pro Spec Table

Best 40mm Gas Filter for Ammonia and Ammonia Derivative Filtration

 AmmoniaPro N-B-1-A Filter Canister

AmmoniaPro Ammonia 40mm Gas Filter Canister

The AmmoniaPro N-B-1-A Filter Canister is exclusively designed to filter out Ammonia and it’s derivatives.   Common applications include deep cleaning or agricultural use.  Some common ammonia derivatives include ammonium hydroxide and ammonium chloride, commonly found in fertilizers and deep cleaning products.

Ammonia Pro N-B-1-A 40mm Ammonia Filter Canister Spec Sheet

Best 40mm Gas Filter for Defense Applications and Filtration

DefensePro N-B-1 Filter Canister

Defense Pro N-B-1 A2B2E2K2P3 R D 40mm Filter Canister

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Our DefensePro N-B-1 40mm Filter Canister is our highest rated defense filter and comes stock on our NB-100 Tactical Full Face Gas Mask. It has a filtration rating of ABEK2 P3 R. This means it filters out a variety of chemicals and particulates including organic vapors, inorganic vapors, acidic gases, ammonia, and 99.9% of particulates. Along with the same capabilities of our AmmoniaPro, OrganicPro, and ParticulatePro, the N-B-1 can filter out inorganic and acidic gases – meaning it’s going to be great against chemical warfare or biological warfare agents such as chlorine, hydrogen sulphide, hydrogen cyanide, sulphur dioxide or hydrogen chloride.

N-B-1 DefensePro Filter Canister Spec Sheet

Make sure you get a proper fit test performed, seal check, and follow all the instructions from the manufacturer’s manual

Hopefully this has helped clarify the differences between Parcil Safety’s 40mm filter options.  We recommend reading through all instruction manuals as well as following the proper steps to perform a seal test, fit test, as well as properly inspect all filters to make sure their packaging hasn’t been tampered with or that they are not visually damaged. 

Finally some things to keep in mind:

  1. It's recommended to be clean shaven when you don any respirator to get a proper seal
  2. We offer the PD Spectacle Kit for those of you that wear glasses and are wanting a full face gas mask. You can purchase it HERE.
  3. If you are planning on using these in a commercial or work environment, please consult with your employer to make sure these models are approved for your use.

Happy prepping and feel free to reach out to us at should you have any questions or concerns!

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