Subscribe for updates and more.

Effective Masks

General statements mean a lot of different things and often apply to a lot of people or items. Often statements are vague or not specific.

Masks are effective” or “Masks are ineffective

Masks work” or “Masks don’t work

Masks help” or “Masks harm

General statements.

Instead, you should be asking:

What is a mask?

What makes an effective mask?

What makes a mask work?

What makes a mask harmful?

“Reality can change as easily as the way you care to see it. An answer, static in nature as it is, refers to a frozen snapshot of that reality. It’s value can only go down.” — A day at the park

You see, general statements are answers. To understand things, you need to ask questions.

Don’t accept answers that you don’t understand. No matter how many other people try to convince you of it, or how many other people believe it, until you can’t convince yourself of it, don’t accept it.

Back to our new questions.

What is a mask?

Merriam-Webster: a cover or partial cover for the face used for disguise.

Wikipedia: A mask is an object normally worn on the face, typically for protection, disguise, performance, or entertainment.

Websters 1913: A cover, or partial cover, for the face, used for disguise or protection.

It seems like a stupid question, right? But this hit me pretty hard. This is where arguments about not wearing a mask come from.

Masks are for people who need to disguise themselves! A negative association! But we’re not talking about covering the face for disguise!

Nono, we explicitly want protection. More on this later.

What makes an effective mask?

This is an important part. Effective means “producing a decided or decisive effect.”

Your decided effect changes what effective masks are.

If your desired effect is 100% protection from something, well, you can claim that every mask is ineffective. Nothing fully protects you.

If instead, you ground your desired effect in giving protection—even by the smallest amount—towards something, well, then you can gauge effectiveness.

How can you determine protection? Easy. Physics.

If we’re making this specific to COVID-19, we have to ask.

How does COVID-19 transmit?

COVID-19/coronavirus is a virus. What makes it a virus?

Merriam-Webster: any of a large group of submicroscopic infectious agents that are usually regarded as nonliving extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic material but no semipermeable membrane, that are capable of growth and multiplication only in living cells, and that cause various important diseases in humans, animals, and plants.

That’s a lot to look at. Let’s break it down.

  1. Viruses are little things that grow, reproduce, and break down bodily functions.
  2. They require a host body to do this.

Okay. Not so complex. That’s acceptable.

How do viruses transmit? Because we’re talking about viruses, there’s no need to focus explicitly on COVID-19. COVID-19 is so politicized that I’d rather not.

Here’s a snippet about how variant influenza viruses spread.

Infected pigs cough or sneeze and droplets with influenza virus in them can spread through the air. If these droplets land in your nose or mouth, or are inhaled, you can be infected. There also is some evidence that you might get infected by touching a surface with virus on it and then touching your mouth or nose. A third way to possibly get infected is to inhale droplets or dust containing influenza virus. Scientists aren’t really sure which of these ways of spread is the most common. (CDC, 2019)

Let’s break this one down.

  1. Droplets contain the virus.
  2. Droplets transmit through coughing, sneezing, or touching.

Okay, not so crazy. If I have a sickness and sneeze in your mouth, that’s nasty, and you’re probably going to be sick on multiple levels.

Our desired effect is now protection against droplets.

What makes a mask work?

Our question is now, “what gives a mask protection against droplets?”

After establishing our desire as giving protection—even by a small amount—towards droplets, we can question how to go about it.

Let’s look at a few different masks.

N95 Respirator intended use: Reduces wearer’s exposure to particles including small particle aerosols and large droplets.

Surgical mask intended use: Fluid resistant and provides the wearer protection against large droplets, splashes, or sprays of bodily or other hazardous fluids. Protects the patient from the wearer’s respiratory emissions.

Agh but wait, there’s also surgical N95 respirators!

Surgical N95 respirators intended use: Reduces particles both inhaled and expelled by wearer (plus fluid resistance).

I’ll start by focusing on what makes the N95 respirator work.

Hopefully, you’re asking, “why is it respirator and not mask?”

The difference is essential.

What is a respirator?

Merriam-Webster: a mask or device worn over the mouth and nose to protect the respiratory system by filtering out dangerous substances (such as dusts, fumes, or bacteria) from inhaled air.

Wikipedia: A respirator is a device designed to protect the wearer from inhaling hazardous atmospheres, including fumes, vapours, gases and particulate matter such as dusts and airborne microorganisms.

Websters 1913: A device of gauze or wire, covering the mouth or nose, to prevent the inhalation of noxious substances, as dust or smoke.

Why is this relevant? Intention.

Right, the intention is important, but that doesn’t give us enough.

Intuition points to masks working due to a mesh of fibers with gaps too small for dust and other particles to get through. And the only difference is just the size of the mesh?

But that’s not how these masks work!

The particles they filter are generally much smaller than the gaps in the mask!

Because of how things work at the molecular level, a masks’ goal is to get particles to touch a fiber in the mask.


At a microscopic scale, everything is sticky! The weak attractive force between molecules is strong enough to hold small things in place.

So an N95 mask is mainly effective because with more layers, there are more chances for particles to get stuck.

Particles of different sizes move in different ways.

  1. Larger particles (> 1/1000 mm) travel in straight lines due to inertia.
  2. Smaller, airborne particles are so light that collisions with air molecules bounce them around, moving them in a random pattern known as Brownian motion.
  3. Medium-sized particles are carried with the air as it flows, making them likely to pass around fibers, even with many layers.

The straight motion of larger particles virtually guarantees them to hit a fiber and stick.

The zig-zagging motion of smaller particles virtually guarantees them to hit a fiber and stick.

So how to get the medium-sized particles? By electretizing the fibers in an N95 mask, they gain a long-lasting ability to attract all particles.

But nothing is 100% effective. The number of medium-sized particles that get blocked in the mask gives you the number in the name. When at least 95% of those particles are filtered out, the mask is rated N95.

You can learn more about the physics of N95 masks from minutephysics.

What makes a mask harmful?

A few arguments:

  1. Oxygen deficiency
  2. Reusing the same mask

Oxygen deficiency

N95 masks are estimated to reduce oxygen intake by anywhere from 5 percent to 20 percent. That’s significant, even for a healthy person.”\ — Stanford

This is a real argument and a real problem.

Reusing the same mask

N95 masks are intended to be disposable, but the demand from COVID-19 has led to a global shortage of N95 masks and the reality is that health workers have to reuse them.”\ — Stanford

Filtration efficiency can be reduced by physical damage to filter or static charge degradation.

Masks have tangible downfalls that should not be ignored.

Don’t claim “masks are effective/ineffective”, “masks work/don’t work”, or “masks help/harm.”

The only way a question can prove itself unworthy is by attracting a better question. What does an unworthy answer leave you with?