A Primer on Protective Masks

With disaster management, it's common to hear talk about Gas Masks. Are they useful? Not until they are, and then... with caveats. Here's our take.

April 27, 2020


As we write this, China is desperately trying to contain the nCoV (Novel Coronavirus) while conflicting reports pour out of the nation about the number of infected, the lethality of the disease, and even its origin.

It's our policy to avoid, at all costs, creating undue panic or feeding into the opportunism that surrounds disasters, but whether we like it or not, this is an emergency we've had in the back of our minds as a "worst case" for a long time, and we're late to the party. So let's discuss a very specific topic, and keep in the back of our mind that there's a very specific problem over the horizon. Whether or not the nCoV ends up being a Pandemic (it likely already is, but we won't know for another couple weeks... Edit 2/10/2020: It is).

There's *very* little we can do about that on a global scale, so that leaves us with a single option: Being prepared on an individual, family, or community level.

So, while we can't put a stop to it, what we can do is take some steps here at home to be ready if it does come around.

"Which Mask?": Part I

Testing some kit in the sub-basement of an abandon complex. Very bad air down there.

One of the first questions people want to ask when a disease or chemical threat comes around is "what mask should I get to prepare?"

We're big on not trying to default to the "what should I buy?" question, since equipment is usually no more than 1/3 of the solution... but in the case of inhaled pathogens, there really is no substitute for isolating bodily substances, such as saliva and blood.

Obviously, the best method is avoiding sick people, but here in reality that's probably not going to happen. So how can we prevent exposure?

Generally, masks and gloves are the 'go-to' tools, but it goes a little farther than that. Because the current concern among a lot of people is the nCoV, we have to consider that viruses are extremely small, and filtering them or minimizing exposure require more than just donning a mask and going about your business.

If you're looking for a disposable surgical mask, that is fairly easy, but it gets a little more complicated if you're using a full face mask, so let's talk about that for a second.

Masks are generally less important than which media filter you choose. The military breaks particulate threats into the acronym "CBRN", which stands for:

The most important thing to take away from this is that *each* type of threat requires a specific type of media filtration, and will have varying degrees of effectiveness over a varying timeline. So, how effective a filter is at filtering radiological particulates might be different than how long the same filter will effectively filter viruses. Because of this, we're going to rely on some generalization up front, and we can dive deeper into the science at a later date.

Because we're particularly interested in Viruses at the moment, let's discuss the filters, and then mask selection.

Filter Considerations

Filters rated N95 or above should provide at least some protection from Viruses, when used in conjunction with good habits and hygiene, but it's important to note that because a mask is rated to filter certain types of particulates doesn't mean it can filter *all* particulates across the various CBRN threats. That may be a consideration for you, but most of us don't have much risk from chemical or nuclear emergencies at present.

The CDC has created a handy table both for identifying what each rating means, as well as identifying marks on the masks themselves that certify that they're correct for your use.

Far more important than the mask is the filter. When we're looking for a filter that can handle viruses, we need to be sure that it's rated according to NIOSH standards.

If you're looking for a full tilt mask, in the West NATO has standardized the 40mm threaded CBRN canister filter, which means that once you've nailed down the right filter for the job, most masks commercially available will be set up to mount the 40mm canister.

So when you see that a mask itself is "US MILITARY SPEC!" stop - that's great and all, but the mask matters a lot less than the filter.

Filters for any given mask are rated, usually by NIOSH (national institute for occupational safety and health), which is a branch of the Center for Disease Control and Prevention.

While most of this has been filters as they relate to an actual mask, there are disposable surgical masks available as well, which are *far* less expensive, and far more common. The problem is, they tend to run out pretty quickly, and most are tested against influenza, and not all viruses are the same size. See the (shamelessly taxed) image that compares the size of various viruses and bacteria. You can see there's a massive difference between the E. Coli bacteria and rabies, so be aware of that when you go to select a mask or filter for "biological threats".

On a scale of nanometers, it can be pretty difficult to visualize the difference between infectious diseases.

The Role of Hygiene

No matter what kit we use to protect ourselves, we absolutely can't discuss the topic without saying a couple words on hygiene and decontamination.

If you're not wearing gloves, the mask is only as good as your hygiene. If you're touching doorknobs and other public surfaces all day long with uncovered hands, the second you take that mask off, you're touching your face, and introducing the potential for exposure.

While it's not practical to create sterile fields, we want to have places we can shed garments that may have been coughed on, a place to wash our hands and decontaminate or dispose of masks. After all, if you end up with a pile of disposable masks that are laden with infectious diseases, your risk didn't really go down, the threat just switched locations.

As well, if you're the one who's ill, a surgical mask can help prevent the spread of contamination by way of sequestering coughs and sneezes.

Updated 4/27/2020

Masks typically make it much harder for larger biological vectors to carry the virus to places outside the body; heavier particles such as mucus and spit from coughs and sneezes travel - you guessed it - about 6 feet. The virus can still pass easily through most cloth masks, but if the person who is sick is containing their coughs and sneezes, there's a far lower chance that other people will need their PPE. Obviously wearing a mask when around sick people will help as well.

In addition to larger droplets, there's concern that nCoV can survive for some time while aerosolized; the good news is this usually doesn't happen in the home. Aerosolization is usually the byproduct of surgical procedures in which tiny particles are vaporized and left suspended in the air.

Be mindful of all this. Insomuch as it's possible, when we're sick we should try our best to make sure we don't get our caretakers ill as well. If we're in hospitals, aerosols can potentially travel, so be sure to wear PPE. Assume EVERYTHING you touch is contaminated, from the ATM pinpad to the gas pump.

If you're concerned about the nCoV, the symptoms, according to the CDC, include:

  • -Runny Nose
  • -Coughing
  • -Sneezing
  • -Malaise
  • -Sore Throat
  • -Headaches
  • -Diarrhea
  • -Vomiting

Fans of Stephen King in the audience are probably having flashbacks to Captain Tripps and people thinking they've got the plain old flu. It shouldn't make too much of a difference, since it's viral and as of now there is no herd immunity or vaccine, but it's smart to be looking ahead regarding what these symptoms do in terms of creating vectors for the disease to spread... feces and vomit, runny nose, coughing, and sneezing - all require some sort of sanitary measures, most of all tissues and toilet paper.

If you're dealing with a person who's critically ill and there's no space at the hospital, you may start thinking now about having some extra water (which they'll need to remain hydrated) with some electrolyte mixes, some extra tissue and TP, and some bleach/bleach wipes.

This is getting out towards the periphery of why you probably clicked this link, but these other components of the battle can't be ignored.

Which Mask: Part II

Wish gas mask from China, for the LOLZ. If Lehang8899 isn't using it right now, it probably doesn't work.

Now that we've addressed the importance of an CBRN rated filter and hygiene, we can return to the discussion of the masks.

The short version: this depends a LOT on your budget.

This isn't an endorsement of the company, but if you're looking for a full-face mask, click here for a pretty respectable spread of options. The cheap end for a full-face mask with a CBRN filter comes in right at $80 and range up north of $500.

Sportsman's Warehouse has a US surplus MSA Millennium mask for under $120, which is really similar to the mask I was issued when I first was in the Military. They're reasonably good masks, and that's a decent price... but Caveat Emptor - it's hard to say that they're still serviceable.

Any time you buy something surplus, you're rolling the dice given that these masks were decommissioned for a reason: they have a shelf life and materials and gaskets that, over time, stop creating the seal necessary to guarantee filtration.

Further, I remember being told at one point that our masks weren't to keep us alive during a CBRN attack, they were to ensure we could launch some form of counterattack before we died. Even more to the point, the CDC and NIOSH have strict guidelines that guide the effectiveness of the mask and filter in the CBRN environment:

  • -Proper Training
  • -Proper fitment
  • -Proper sizing
  • -Material free from defects and wear
  • -The mask must be donned effectively
  • -The period of exposure per canister is < 8 hours
  • -A verified proper seal

In short, don't just expect you can buy a gas mask and have a solution. It's not that simple.


So with all this said: be cautious when you're looking for masks, and don't over-react. While the Coronavirus may still see widespread infections, at present you're still more likely to die from complications from the regular old influenza virus. What we've got on our hands right now is a regional Type II emergency. IF it does become a pandemic, which is still a reasonable possibility, it could result in widespread interruptions to normal infrastructure.
We know what to do about that.

If you can't find specifics on the mask/filter's rating and capability to filter out viruses, hold back. As we saw in the image above, viruses are *tiny* compared to other particulates, so what works on Asbestos probably isn't going to do anything for you if you're being coughed on, or you're sitting next to someone sneezing on a Subway train with recirculated air. Even under the best conditions, simply having a mask isn't a guarantee you'll be kept safe from all possible CBRN threats, so don't forget the habits that go along with protecting yourself from immediate exposure.

We often use the 3M 6200 for exploring in places with bad air, and 3M Also makes some respirator and full-face masks that are rated for biological contaminants. They've got replaceable cartridges and can be had for between $20 and $120, making them among the most reasonable options.

So while we can't say which is the best for you, most people will be pretty well protected with any 95+ rated mask and good hygiene.
Here are a few to consider:

These masks give a good cross section of what's available, and with exception of the 3M 07163, the ISG team has used all of these masks in some capacity, and we can recommend them as effective and serviceable masks for disasters that involve CBRN threats. With that said, having a simple, effective, and reusable respirator, so good habits and hygiene, and some applied awareness will probably take you farther than buying the most expensive mask and expecting it'll do all the work.

The key takeaways for those new to protective masks are:

  1. Masks are a tool - they require knowledge, training, and upkeep, just like all other tools.
  2. Masks will not eliminate risk - they'll help you mitigate it when used correctly.
  3. Not all masks are good for all CBRN threats. Assess your risks reasonably and realize the 'best' solution might be the most simple.
  4. Don't ignore the secondary and tertiary effects of the fears pandemics create - be ready for a Type II emergency.
  5. Consider the uses you have for a mask/respirator. If you have one you use normally, it might be wise to upgrade to one that can be used for organic threats as well as occupational particulates.



Special thanks to Dr. Doug C., who was gracious enough to discuss his take and experiences with nCoV so far.

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