What Marjorie Taylor Green doesn’t know about masks… or underwear

Week after week, the competition for greatest Marjorie Taylor Green parodist on Twitter has one clear winner: Marjorie Taylor Green. And a few days ago she showed everyone else why she’s still the champ:

(Tweet text: “So many people still wearing masks. I just want to ask you. If a pair of underwear, really thick ones, high quality cotton, can’t protect you from a fart, then how will a mask protect you from covid??”)

This tweet has been living rent free in my head for days. It’s clearly crazy, but not so crazy that it completely defies any attempt to respond. So for reasons I don’t quite understand — and against my better judgement — I’m going to attempt to answer the Senator’s question.

At its most basic, the answer is that underwear is not a mask. Masks — at least the kind of masks people wear to avoid COVID-19 — are specifically designed to filter the air passing through them. But until seeing this tweet, I had never considered that someone might expect underwear to filter out the smell of farts. As far as I knew, that’s not what underwear is for.

When it comes to the SARS-Cov-2 virus that causes Covid, there are a couple of common ways it spreads. In the early days, it was mostly thought to be a matter of droplets blown into the air by a cough or sneeze. These droplets are relatively large, often large enough to see with the naked eye, especially when lit correctly, as in this photo of a sneeze:

As you might imagine, almost any cloth placed over the nose will absorb some of that mess, possibly even underwear. I have never seen a similar photograph of a fart,^[1]If you have one, do not send it to me. And don’t tell me why you have it. but if farts were composed of droplets, then underwear would soak up most of them. But since we can still smell farts^{[citation needed]} we know that a meaningful amount of the fart smell escapes capture by underwear.

It might just be that the underwear is absorbing most of the droplets, but that our noses are sensitive enough to detect the relatively small percentage of fart droplets that escape the underwear. I’ve never checked (and I don’t want to know), but it could be that most farts would smell much worse coming from a naked butt. When someone farts in the office, we might only be smelling, say, 25% of it, leaving us to wonder if eliminating 75% of the droplets is better than nothing.

With Covid, the answer is a clear “Yes” because it turns out that Covid exposure has a dose effect: The more Covid virus particles you are exposed to, the more likely you are to catch it, and the worse it’s likely to be. This means that even a poor mask material (like underwear) could reduce your Covid exposure enough to offer some protection.^[2]If the people coughing up the Covid are also masked, we get an even greater benefit since that reduction occurs twice. A 75% reduction might not be enough to keep us from smelling a fart, but it could keep us from catching Covid, or protect us from a severe case of Covid.

Unfortunately, filtering out droplets is not enough to protect us from Covid because the SARS-CoV-2 virus can also travel as an aerosol — a fine invisible mist that lingers in the air for many minutes. A loosely woven piece of cloth like a pair of underwear won’t do much to stop aerosol particles flowing through the gaps between the fibers. And so, in a sense, Marjorie Taylor Green is correct: For the most part, underwear won’t stop Covid.

Which is why we wear masks not underwear.

The material that makes up most surgical masks — and all N95 and KN-95 filtering face piece respirators — is a non-woven material that provides a dense microscopic forest of fibers specifically designed to filter particles from the air. It traps larger particles simply because they are too big to fit between the closely-space fibers of the filter. Smaller particles fit through the gaps between fibers but they are still trapped when they slam into a fiber and stick to it through one of several chemical, mechanical, or electrostatic mechanisms. Think of it this way: To a virus particle 0.1 micron in size, a piece of filtration material a millimeter thick is a forest of fibers 10,000 times its size. That’s a long way to go without getting stuck to something.

These kinds of respirators have been in use healthcare and other industries for decades, and are well understood. They are known to easily filter Covid-sized particles, and they’ve been tested against actual Covid in the lab. At the risk of repeating myself, masks filter Covid from the air better than underwear because masks are designed to filter things the size of Covid from the air.

In the replies to Marjorie Taylor Green’s tweet, some people comment that they can still smell farts while wearing a mask.^[3]They don’t say what kind of mask, but let’s assume it’s an N95 or equivalent. This suggests that whatever it is they’re smelling is neither droplets nor an aerosol — both of which would have been almost entirely removed by the mask.

I was unable to verify what fart smells are made of,^[4]And I have exhausted my tolerance for clicking on search results about farts. but I can make a pretty good guess at what to do about them. I think if the Marjorie Taylor Green crowd are really concerned about fart smells, the solution is probably an activated carbon (charcoal) filter mask. Activated carbon is spectacularly porous giving it a huge amount of surface area — an ounce of activated carbon has almost a million square feet of space. The molecules of fart gas passing through an activated carbon filter should get stuck somewhere on that vast surface, leaving nothing but clean air.

I can support this guesswork with two real-world data points: First, cat poop and human poop can’t be all that different,^[5]We’re all mammals, and we eat the same kinds of food, and what goes in must come out. and I can confirm from experience with litter boxes that activated carbon air filters eliminate the smell of cat poop. Second, it turns out there actually is a brand of underwear designed to absorb farts, and it uses activated carbon as well.

I’ve not seen filtering face piece masks that have activated carbon filters, but if fart smells are a serious concern, you can get activated carbon filters in elastomeric half-masks from Home Depot.^[6]This was my sneaky attempt to trigger anti-maskers.

The tl;dr version: I expect my masks to stop Covid because my masks are designed to stop Covid. If Marjorie Taylor Green wants to stop farts, she’s going to need activated carbon filters, not underwear.