A common improvised dust mask is taking a bandana and tying it over your nose and mouth. I'm asking this question because I'm wondering what else one could add to this set up if anything. First, I'd like to say I'm not knocking the classic cotton bandana dust mask at all; in fact, I appreciated its simplicity.

As for the use case or hypothetical scenario, we can assume it could be anything from pm 2.5 ridden smog that the wind blew over from a nearby city or factory unexpectedly. Or it could be a dust storm kicking up in a desert setting. It could be any number of things. To my knowledge, a cotton bandana would only offer limited protection in these hypotheticals. I'm hoping there is a way to improve it.

Ideally, we would research the area and bring gear accordingly. However, suppose we were caught off guard but we still wanted to make the best dust mask we could to protect our lungs. Going with the pm 2.5 issue again, this would normally require a specific, professional-grade mask. I don't hope to improvise anything better than that of course, but maybe there is a way to improve over the cotton banada? The cotton bandana can serve as a baseline.

One Idea I had:

The only idea I had using materials that an outdoorsman would conceivably have on him would be to nestle some activated carbon (useful for filtering among other things) in between the folds of the bandana. If it could somehow be secured there, would that not help a little with the pm 2.5 or other harmful particulates?

Question: If my idea doesn't sound plausible, is there any way at all to improve upon the cotton bandana using reasonably common outdoorsman supplies? Or are we 100% doomed to suffer the full extent of pm 2.5's microscopic wrath without a professional-grade mask? What about for the case of a natural desert dust-storm?

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    +1 As can forest fires. See this answer
    – ab2
    Aug 23, 2018 at 12:50
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    The bandanna can help, sure. The activated charcoal just means all the air goes through other parts of the bandanna. But, for real protection you need a real respirator (and, no, the stupid white things with an elastic strap that go over your nose/mouth are not real respirators since they don't have a good seal, so most of what you breath comes around the edges without filtration).
    – Jon Custer
    Aug 23, 2018 at 15:17
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    @mmcc It depends on how fine the charcoal (assuming that as carbon source) is and whether it is packed tightly or allowed to move and flow with the medium flowing through it. With my water filters, if I oversaturated them so that the particles could float around, it didn't work as well, but if held packed together or if not over-saturated, the water came out looking clean enough to drink. Now, air is a magnitude harder to deal with, but still if the filter is fine enough it will filter out some, and if it is thick enough (that's something I forgot to mention in my answer), then it (1/)
    – Loduwijk
    Aug 24, 2018 at 0:26
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    (2/2) ... will also work better, especially for purification. The more carbon the medium needs to flow through, the more it will filter out and the more toxins it will trap in its pores. So anything larger than the largest space between filter particles will be filtered out, anything very tiny will get soaked into the carbon pores, and I suppose that could leave a mid-range that you fail to account for... but whether that matters depends on what exactly is in the air (dust? check. sand? check. CO2? probably but don't risk it without test. smoke? mid-range I don't know)
    – Loduwijk
    Aug 24, 2018 at 0:32
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    @mmcc Sorry, I think my previous comment was misleading in how I worded it. 1) Yes, for the filtering specifically, it does not matter what you use. You can use anything that will physically filter out particles larger than the gaps in your filter. So for very specific use cases we might be able to get away with other mediums. Sand storm? Maybe you can use sand itself? Though I would guess the airborne sand particles would be on average smaller than the ones still on the ground and maybe could slip through. 2) When I said it works better if thicker, I did not mean the particle (1/)
    – Loduwijk
    Aug 24, 2018 at 12:28

3 Answers 3



Yes, carbon might be your best bet. I would not bet my life on such a thing if I had not already practiced it though. Carbon is used to filter purify both water (your typical Brita water filter) and air (re-breathers for divers' air), so the potential is there. Farther down I discuss how I would approach this since I have made filters before.

I have heard claims that simply wetting the bandana can improve its filtering ability. I have never seen anything to lend great credibility to this, but it makes sense. It probably would not improve by much though, as all it would take is 1 small spot to dry up for the air to go through that spot instead. Maybe if you kept soaking it frequently, but then you would need to be stationary and constantly dipping your face into a lot of water. This does not sound like something I would bother to try except in an emergency in which I was stuck in one place anyway.

As far as crafting something, yes, good carbon would be the first thing many of us would think of. I will warn you from experience though, as I have been doing a lot of playing around with this kind of survival crafting; you need to be careful or you could just make matters worse for yourself by inhaling the carbon dust, ash, or other fire byproducts. I accidentally did this recently and got a face and breath full of stinky fire byproducts and did a lot of coughing for a few minutes. Maybe you could improvise a dust mask for... never mind. ;)

If you want to go the carbon route

Obviously you need a source of carbon

I am going to assume that you are sourcing your carbon from the wild rather than bringing activated carbon with you on your trip.

First, make sure you actually have good carbon for this. Simply taking the black stuff out of a fire is not going to give you the best charcoal. You need to make sure that you drive off as much of the non-carbon chemicals as you can from the wood. I won't go into details, as that would be an answer to a different question ("How do I make good charcoal?" could be a good TGO.SE question if not already asked, or you could Google that). But I will say, since many charcoal tutorials don't, that if you want as pure carbon as you can get, make sure you burn it hot. Different chemicals come out at different temperatures, so you can have what looks like great charcoal that could still be reduced closer to pure carbon if it comes from a low-temp fire.

Preferably activated carbon (though not necessarily)

Even if you get as good quality charcoal as you can, calling it "activated carbon" is still questionable at this stage. Different people mean different things when they say activated carbon. Usually it is considered activated when you have processed the carbon by increasing the size of the pores within it. There are various ways of doing that to activate your carbon, most of which are not applicable to the situation you describe. Again, I will gloss over the step of activating and suggest that is another question ("How can I activate my own carbon?"). Even if you do not activate your carbon, that doesn't mean it is useless for your situation. Activating it just makes it work better.

It should be powdered carbon

So let's say you have made good charcoal and want to use it as your source of carbon in your mask. Generally, carbon is ground into powder so that the gas or liquid to be filtered and purified can move through it. In the situation you describe, you should just make it into the finest dust that you are capable of. When I have done this in the past, I have set the charcoal out on a flat surface and broken it with a stick until it was small pieces, then squished the small pieces with the end of the handle of my knife. If that doesn't get it small enough, I just try to find whatever nearby seems like it will work best to get it into a powder. If you have good stones for grinding, that could work; preferably non-porous stones so it doesn't get caught in the stone.

Now to make the device...

Now you have your filtration/purification vector, the carbon, but you still need to get it into a form that will actually work for you. This is where your situation is going to start diverging from my experience unfortunately, as I have done this to filter water for drinking but not air for breathing.

When I did this in the past, I would use paper if I had it, or the biggest leaf I could find, fill it with the pulverized charcoal, poke some tiny holes in the bottom, and start slowly filtering water through it. Even the muddiest, nastiest, dirtiest water came through looking clean as bottled water out the bottom.

For you, though, we need to get it over your mouth and the air moving through it...

If I were to attempt this, I would fold the bandana over once or twice if it's big enough, to add more layers to help keep charcoal out of my mouth. I would mix some water with some dirt to make some mud and make a circle of mud on the bandana. Not thin, runny mud, but rather thick mud that will hold its shape well, to make a little circle wall about the size of my mouth opening. Fill it with the carbon (crunched, good quality charcoal), and put something on top of it to hold the charcoal in. My first guess is a leaf with little holes poked into it, though I'm not sure how well that would work... I (and you) would have to experiment a little.

Once all that were made, I would hold it up to my mouth and seal the edges with more mud so that air cannot go around it.

My thoughts on this device

So there is a forest fire nearby and the smoke is choking you out - this is not the time to be wasting on crafting the thing I just described. You would be much better off just getting yourself out of the forest fire.

So a dust storm kicks up - if you had no advance warning, you have no time to make this. If you do have advance warning, hopefully making this device is not your best option available.

If all you have is the bandana and your other normal gear and you want to make this, it will take hours. If you want really good quality charcoal in the setting you describe, you generally don't make it and use it same day, rather you make it (in the fire) and use it next day after it has thoroughly cooled. So it will take an hour to a day just to get the charcoal if not already available, then gathering the other resources and crafting it takes a while too. It might sound simple, but it's not. The water filters I make are more simple than this, and I usually have to make a few attempts as parts break during the process.

I would guess that it would take me at least a few hours the first time I tried to craft this and have it ready to use, and that is if I had all the pieces on hand ready to start putting them together. After making a few practice ones, and if I can get it first try without having to redo anything, then maybe less than an hour.

And even then, this is just an educated guess since, again, I've done water filters but not air filters. Carbon is used to filter air too. Activated carbon is one of the materials that can be used to make diving re-breathers, so we know this is possible. But in the situation you describe, this would definitely not be the first thing I tried, and it might be the last.

Update: First attempt was not successful

I tried this out today. For the first attempt, I did not go all-natural. Instead, I used a disposable water bottle for the base, similar to the answer by Restless Adventurer. That should have made it easier, yet I still ran into problems.

The major problems with the device I made:

  • Very difficult to breathe out. I would make a looser seal next time so air can escape around my mouth instead of trying to force it through the carbon filter.
  • In was easy, but only because the carbon shifted out of the way and the air went around the carbon instead of through it. Next time I would try to use something to hold the dust in place better.
  • Some of the dust came out into my mouth and lungs. Very unpleasant. Again, hold it in place better with something that the particles won't go around.

After the above changes, I fear that the air might have much difficulty coming in to inhale as well. Might need to make the powder layer less thick, though it already wasn't thick to begin with.

I would not dismiss this mask idea entirely, but it is not looking promising. I would not bother trying in survival scenario unless I had lots of time to tinker and could use the results in a controlled environment.

  • See discussion in comments on question on how carbon works / doesn’t. Just also wanted to say that I appreciate the process you suggest here: prove it works and practice it at your leisure, then think of it as a thing to you might do in the field.
    – mmcc
    Aug 24, 2018 at 1:38
  • @mmcc Edited: added new section at end with first test I just did today. Unfortunately, not successful. I am less hopeful than before. Even if this can be managed, I would not rely on a quick ad-hoc implementation in the field for an imminent threat. It needs to be a long, draw out R&D in the field and used in a controlled environment. :(
    – Loduwijk
    Sep 29, 2018 at 18:21
  • @mmcc Of course, I am going the "protect against everything, even micro-threats" route. You had a good point in your answer that I could just scale up the filtration particles, reducing the protection level but increasing the breathability.
    – Loduwijk
    Sep 29, 2018 at 18:22

There are a number of plans using 2 liter plastic bottles for improvised "gas masks". Note that they would not stop gasses but instead filter out particulates like from a dust storm, collapsed building, forest fire, pepper spray, etc.

The basic gist is to cut a U shaped face hole or mouth/nose hole in the bottom of the 2 liter with the cap side pointed down. The cap area can be stuffed with whatever filter material you can find. There are numerous different instructions of varying degrees of sophistication.

  • Although your answer requires you to have that extra object on hand, assuming you do have it this would be much faster than the all-natural route I suggested. In fact, I wonder if you could make this fast enough that it could be useful even in the emergency situation you might actually need it in, which is not likely with mine. +1
    – Loduwijk
    Aug 23, 2018 at 18:34
  • True its more of an urban item but 2l trash can be found all over the world. I can imagine an ash cloud or debris from a collapsed building rolling through a downtown area. A person could duck into a 7/11 and come out with fairly decent 2l mask with coffee filter elements and maybe a duct tape seal. Or in the wild picking up a crushed 2l off the beach or in alluvial deposits and using moist wadded cotton and holding it to their face. I bet the second time around it would be a pretty quick build. Aug 23, 2018 at 21:28

Working answer:

In case of truly irritating particles (bad enough that the breath-moistened bandana ain’t cutting it): Poke many small holes in bottom half of a disposable water bottle. Pack bottle tight with porous / fibrous / granular material. Put mouth over the bottle opening and breathe like a snorkel. Improvise nose plug. Exhale by opening mouth. If you can’t breathe enough, pack less tightly or use coarser particles/fibers. If you’re still breathing too much of the irritant, pack more tightly or use finer particles/fibers. Possibly moisten. Ideally practice this sometime in the actual terrain where you travel, with some irritant source like a smoky campfire blowing in a steady direction / dust kicked up deliberately that you can escape at will.

Full answer:

I’d like to suggest a means of dividing this problem into pieces, in the hopes people so inclined can use comments to suggest solutions to the particular pieces they understand.

Possible means of sealing to airway (within following categories): Tube in mouth so that lips provide seal, in conjunction with nose plug (style of snorkel/scuba/bong) Covering nose and mouth, sealing against skin (style of respirator) Covering face, sealing to face (style of gas mask) Covering full head, sealing to neck (style of emergency fire evacuation mask)

Possible means of allowing the passage of inhaled air sufficient for a given level of exertion

Possible means of exhaling w/o co2 buildup

Possible means of immediate removal to prevent suffocating if clogged

Possible means of blocking a certain appropriate percentage of a certain size particulate, via possible mechanisms including: Holes too small for particle. Sticky passages that adhere particles.

Other possible features: Reduction in noxious gasses Eye protection Completely hands-free use Filter purging / cleaning

Possible means of testing efficacy w/o injury

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