Gas Masks And Respirators For Preppers

Gas Masks, more technically referred to as respirators, are quite a specific tool that have been dramatized a lot by Hollywood. In reality gas masks have a very limited use case and are overkill for a lot of situations, but are essential, life saving pieces of gear in others.

This guide will talk you through all aspects of respirators from what you might use them for to filter selection to fitment. We will be focusing on full face military style gas masks but half/full face commercial respirators will do a similar job.

When Would You Use A Gas Mask?

Gas Masks fall under the CBRN umbrella meaning they are intended to protect you from Chemical, Biological, Radiological and Nuclear threats. While they will protect you from all of these they are by no means essential for some of them.

For example: A gas mask would have protected you against Covid-19, but so would an N-95 mask (albeit not quite as well). They would both do the job equally well.

The same applies to nuclear and radiological threats. In fact in any threat that is just particles in the air, such as viruses or fallout, you will be served almost equally well by an FP-3 mask as a respirator. The drawbacks of an FP-3/N-95 mask is that it only protects you from inhaling the particulates while a gas mask will protect your eyes and skin as well. This offers better protection from alpha and beta radiation and stops you viruses infecting you via your eyes.

So where is a gas mask essential then? In chemical threats an particulate mask will not do the job. This is the case for threats such as CS (tear) Gas, Carbon Monoxide, nerve agents, solvents and the majority of chemical weapons. For these threats other filtration methods are used.

Gas Mask Filters

One of the benefits of respirators is that a lot of them can take multiple types of filters. This means that you can change the filters based of of the situation you are in. Also please note that no matter what filter you have a mask cannot help you if there is no oxygen. There have been a few cases where people have entered fires with gas masks on only to perish as the fire had consumed all the available oxygen.

A P3 40mm NATO Gas Mask Filter
A P3 40mm NATO Filter

Filter Attachment

There are two common types of attachment. Most military Gas Masks use a 40mm NATO (also known as STENAG 4155 or commercially as RD 40) thread and most commercial respirators use a 3M attachment. A P3 40mm NATO filter is shown in the image.

Some noteworthy exceptions to this rule are the old Soviet style filters (which also used a 40mm attachment but had different threading and so aren’t compatible with 40mm NATO masks), the M50 Series Masks, the British Army Scott GSR, and the US M17 Mask and its clones.


Most Gas Mask Filters usually comprise of three layers:
The Particulate Filter: This is a filter similar to the one found in FP-3 masks. Depending on the filter make they can filter particles down to between 1 and 0.3 microns in size.
The Chemical Filter: This is an activated carbon layer that will react with organic chemicals and toxins. It is often mixed with metal oxides to combat more specific threats. The reason gas mask filters expire is this layer as the activated carbon can react with gases in the atmosphere.
The Dust Filter: The final layer is a simple dust filter to stop you from inhaling the activated carbon in the previous layer.

You can also get some filters that just have the Particulate layer which are far cheaper, do not expire and will adequately protect you against Nuclear, Radiological and Biological threats. They are also easier to breath through.

The ABEK System

Filters are rated according to the ABEK standard. A letter and corresponding colour is given to to filters to show the threats they can protect from. Each of these threats is then rated as class 1, class 2 or class 3 protection. Class 1 offers protection from concentrations up to 1000 parts per million while class 2 offers protection up to 5000 parts per million and class 3 will protect you up to 10,000 parts per million[1]. Some companies will then add a ‘P’ designation onto the end which is its particulate filtering ability. This is rated from 1-3 using the same system as the FP-3 type masks.

Other filters may have a solid block of colour indicating that they area multi-gas filters.

A Sealed Multi-Gas Gas Mask Filter
A sealed Multi Gas filter
ABEK gas mask filter rating
ABEK Colour and Letter Codes (Image Source)

Filter Wear

As well as their expiry date you should also be aware of how long a filter will last in use. Most filters will give you an idea of how long they will protect you for although this will depend highly on the rate at which you breathe, and the concentration of the toxins.

Particulate filters have no limit to how long they will filter for as more particles getting stuck in the filter will just increase their effectiveness. They do get harder to breathe through over time though.

Your filters expiry date relies on you keeping in in its packaging. Most will come vacuum sealed in plastic or Mylar with a top and bottom cap on. This is because the filter will react with atmospheric gases and degrade over time. You can take the filters out and use them and then seal them again but this will drastically decrease their expiry. In a pinch filters will still be somewhat effective against chemicals after they expire and no matter how far past their expiration they are they will always still filter particulates.

Gas Mask Fitment

An essential part of ensuring your mask works properly is the fitment. For a proper gas tight seal you should be cleanly shaven and have no hair between the mask and your skin. In the movies it is sometimes shown that people put gas masks over the top of balaclavas. Don’t do this, it will ruin the seal, your mask should be applied directly to your skin.

The mask should it over your chin so that when you talk it doesn’t form a gap. It would also be tightened up so it doesn’t slide down your face as you walk. You should have your straps pre set to the correct tightness so when you need to put it on fast you don’t need to adjust them.

You can check the masks seal by covering the intake and trying to breathe in. If you have a good seal it should pull a vacuum. You can then screw on your filter, ensuring you have first removed the cap on the intake of the filter as failing to do so can lead to suffocation.

Buying Gas Masks

If you can afford it the best choice is always to buy knew. The current leading provider of civilian gas masks is MIRA Safety. They do a range of civilian and military masks as well as masks for kids. They also offer long storage life 40mm NATO filters. You can also look at 3M for more commercial style masks or half face respirators however these are more tailored to industrial applications than CBRN emergencies. If you want a cheaper alternative then you can look at the surplus market.

Surplus Gas Masks

The surplus market is very hit or miss so it is important you know what you are looking for. A lot of masks have obsolete or hard to find filter attachments. Make sure to go for a 40mm NATO filter as they are the easiest to come by. Also be careful as some older masks contain asbestos in the filters or padding, and the rubber in masks can crack over time leading to leaks. Here are a few good models to get started with:

Avon S10/FM12/CT12:
The S10 was adopted by the British Forces between 1987 and 2012. The FM12 replaced the S10 but was still very similarly built. The main differences included the straps and the the mask sitting closer to the face with a lot of the bulk removed. The FM12 was also used by police forces around Europe and America. The CT12 is a rare variant of the FM12 designed for counter terrorism. Its only real difference is the removal of the drinking straw system. They all take 40mm NATO filters and have been in service recently and widely enough to be easily found in good condition. These masks are also designed for the military meaning they work well with rifle scopes and you can find attachments such as anti flash and night vision lenses on the after market for them.

S10 Gas Masks
An S10 Gas Mask

Israeli 4A1 Civilian Gas Mask:
These masks have been issued to the civilian population of Israel since the Gulf war and can still be found in service today. They are designed to be a one size fits all mask that will fit children down to 10 years old (The image shows an 8 year old wearing it with a good fit). This design does mean that they are not the most comfortable and they are far from tactical but will still do the job of saving your life. They also have very limited vision due to the small eye holes. As they are still in production they can be found in good condition and quite cheaply on surplus markets. They also take 40mm NATO filters. You can also check out the Israeli M15 Mask which is their military version.

Child wearing Israeli 4A1 Gas Mask
An 8 year old wearing an Israeli 4A1 Gas Mask with a good fit.

Gas Masks and Filters to Avoid

Soviet GP-5 Masks and Filters:
This mask is a no go as the filter uses the Soviet 40mm threads so isn’t compatible with modern 40mm NATO filters. Not to mention that a good majority of the masks used asbestos in their filters. The Soviets failed to phase asbestos out even after they knew its affects and filters dated as late as the 1980s have been known to contain it. Given that production ended in 1990 this doesn’t leave you with good odds.

American M17 and Clones:
The American M17 is a cheek filter mask that has a multitude of issues. The filters for it are no longer made and it is very hard to find old ones (they are also all likely expired now). The rubber it was made of is known to degenerate overtime such as copper poisoning (where copper ions permeate the rubber causing it to go brittle) and forming to positions it was stored in for longer periods. There were also issues changing the filters on this mask as it had to be done from inside meaning you would have to decontaminate and remove the mask to change them.

Old Filters:
Old filters pre the 1970s are known to contain asbestos as mentioned previously. Older filters have also been known to be painted with lead paint which can cause heavy metal poisoning. Another heavy metal sometimes found in older filters (and occasionally still used today) is chromium which can lead to an increased risk of cancer. Filters also expire as the chemicals in them react with atmospheric gases, meaning they wont protect you from the threat.

Scott GSR and Avon M50:
These are both modern masks in current use by the British and American military so they will be in good condition if you can find them. The issue is that the filters are very hard to come by as they are not 40mm NATO.

Scott GSR Gas Mask
Scott GSR Gas Mask

If you have enjoyed reading this article you can learn how to build a Nuclear Survival Kit to go with your gas mask in this article or have a look at some of our others here:


[1] Vandeputte Safety Experts, “ABEK gas filters: what you need to know”, accessed 08/02/2023

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