Hey, smart people, Joe here.

Bottom line, masks work.

They are safe for almost everyone to wear.

And the more people that wear them, along with adhering to physical distancing and other strategies, then that is more lives that we will save.

Now, a ton of people have watched my last video that clearly demonstrates why simple cloth masks work to slow the spread of diseases like COVID-19.

But there is still a lot of confusion and misinformation out there when it comes to both wearing masks and the actual risks of getting infected with COVID-19.

So today, we're going to be addressing a few of the most common myths and misunderstandings with scientific evidence.

[MUSIC PLAYING] Let's address some of the misunderstanding and misinformation out there around masks and COVID, starting with... (farts).

Seriously, I see this claim a lot, so I have to go there.

"My underwear and pants can't stop a fart, so how is a cloth mask supposed to stop coronavirus?"

Yes, we're actually going to talk about this because it illustrates some really important points about why masks work.

Now, these are the gases in a typical fart.

Most of them are odorless.

But every ounce of flatulence has trace amounts of these other gases, and these are the ones that, well, shall we say, make their presence known.

But one fart smell molecule is less than a billionth of a meter across.

A coronavirus is more than 100 times bigger than that.

And these are the droplets coronavirus is actually transmitted inside.

Remember, when people breathe out the coronavirus, it's ejected out in droplets of moisture that are way bigger than the virus.

Wearing a mask catches those droplets and protects other people from you possibly spreading the virus.

Let me put it like this.

If a fart smell molecule was a baseball, a respiratory droplet full of coronavirus would be as tall as-- holding for zoom-- the world's tallest building.

I almost can't believe that this is a real experiment, but years ago, scientists actually tested whether it was safe for doctors in the operating room to pass gas, whether they could potentially infect their patients with bacteria or other germs ejected from you-know-where.

So they had doctors pass gas over Petri dishes with and without pants on, and pants were enough to block any germs from growing on the dishes.

So even though your underwear won't stop a fart, they will stop a [BLEEP].

And that is why masks work.

OK, another claim that I see a lot is using a mask to stop coronavirus is like using a chain link fence to stop mosquitoes, the idea being that the weave in a cloth mask is supposedly way too big to catch those super tiny particles.

And it is correct that a single coronavirus particle is very, very small, something like 100 nanometers wide.

But again, these viruses are ejected from an infected person's airway inside much larger droplets, 50 to 100 times larger than a single virus.

Here's the weave of a typical cloth mask under a microscope compared to the size of typical droplets.

And here are some other commonly used mask fabrics.

Now, none of these fabrics will stop 100% of virus particles from escaping, but experiments do show that any of them will give you good droplet-blocking power.

This isn't just about the size of the holes in a fabric weave, it's also about how the fibers within the fabric are layered and stacked.

We can see that by looking at the fibers in a medical mask.

It's more like a rat's nest than a weave.

By layering household fabrics, we can get some of that effect.

So a chain link fence can't stop mosquitoes, but two overlapped chain link fences can definitely stop mosquitoes if they're flying around inside tennis balls.

OK, here's another misconception.

Wearing a mask can supposedly starve your body of oxygen or expose you to dangerous levels of exhaled carbon dioxide.

Now, if you're not used to it the way that doctors and nurses and scientists are, breathing inside of a mask can feel very stifling and strange.

But most of that is just the mechanical slowing of the airflow by a mask.

It just feels weird.

And like we saw with farts, gas molecules like CO2 or oxygen are thousands of times smaller than the particles a mask actually blocks.

The amount of CO2 that might be hanging out in your mask is not dangerous.

This is the air that we inhale, and the air that we exhale looks like this.

Yes, we do breathe out CO2 at a higher concentration than we take in, but the atmospheric CO2 concentration is so low that most of what you breathe out just diffuses away through your mask very quickly.

I mean, that's just basic chemistry and physics.

And carbon dioxide, well, it's not always bad.

Breathing out too much CO2 is actually why you feel dizzy from hyperventilating.

Now, accumulation of CO2 in the blood, called hypercapnia, can be dangerous.

But it's not likely to happen from wearing a mask, even a N95 mask, for long periods of time, and especially not when you're just popping on your mask to run into the grocery store or something.

Now that said, if you have a serious respiratory condition, like COPD or other lung problems, definitely talk to your doctor about your mask concerns.

Or go leave a comment on a Dr. Mike video.

-He loves that stuff.

-[INAUDIBLE] There's also the issue of not getting enough oxygen, or hypoxia.

But according to the American Lung Association, there's no evidence that dangerously low oxygen levels can occur from wearing a face mask.

And I've been wearing six masks for like five minutes, and this fingertip oxygen meter tells me, well, I still got 99% oxygen saturation, which is like an A-plus.

Go me.

There we go.

See?

Look at that.

Oh, it's down to-- oh, 99 again.

A-plus.

OK, I don't want anybody claiming I don't actually-- what was that?

I don't want anybody claiming I don't really have six masks on.

One mask.

Two masks.

Three masks.

Four masks.

Five masks.

Six masks.

Now again, wearing a mask may make it feel like it takes a bit more work to take a breath, but it will not materially change the makeup of the air that comes in and out through the mask.

OK, and speaking of breathing things in and out, you may have heard that wearing a face mask will stop your body from being able to expel toxins that it needs to get rid of.

But that's not really how this works.

Our airways are not the primary exit path for the vast majority of your body's unwanted waste materials and byproducts and toxins, and neither is sweating for that matter.

That's a common misconception.

Most of your body's self-cleaning is done by major organs, like your liver and your kidneys, which use special proteins and enzymes to break down and remove anything that's unwanted or harmful from the body.

And that's typically excreted in your urine.

I mean, there's a reason doctors screen your pee to look for stuff.

Your respiratory system is involved in cleanup, but not because you breathe out a stream of toxic junk.

Particles that make it into your nose or airway or lungs are coughed up or they're swallowed in mucus, and masks are actually helping block that stuff in the first place.

Typically, the only hazardous thing we breathe out is carbon dioxide, and we've covered that.

And if you are infected with coronavirus, wearing a mask isn't going to make your infection worse.

Coughing out virus isn't what cures you when you're sick.

It's the virus's way of ensuring it infects another host.

So a mask will help slow that down.

OK, next misconception.

"I feel totally healthy and normal, so I don't need to wear a mask."

OK, even if you feel healthy, you could be infected with the virus and be spreading it to others.

Current estimates tell us that almost half of people who spread COVID don't show any symptoms.

They're either pre-symptomatic, or in some cases, never show symptoms, even if the virus is replicating in their body.

Let's do a little thought experiment.

Say you got infected with COVID-19 three days ago, and then today you go and get a test.

With current testing backlogs in some places, you may not get your results for several days after that.

And even if you get a positive test and immediately quarantine, that is maybe a full week that you could be walking around with no symptoms potentially passing the virus to others around you.

And new research suggests a lot of the pandemic is being driven by so-called "superspreaders."

These are single highly infectious people that are spreading the virus to dozens of other people at a time, and those people might not show any symptoms ever.

So just because the person next to you looks totally healthy does not mean they aren't infected.

And ask yourself, would you feel better if they were wearing a mask?

Well, they feel the same way about you.

OK, next misconception.

If masks aren't 100% effective at stopping coronavirus, then why should we even use them?

OK, well, first off, there's pretty much no medical intervention of any kind that is 100% effective.

Even a vaccine, which most scientists and doctors think is by far our best strategy for eventually containing this pandemic, won't be 100% effective.

A good vaccine gets close, but nothing is perfect.

And from the very beginning of mask recommendations, the idea has been that masks are just one part of a bigger strategy that includes physical distancing, good hygiene like handwashing, and staying home whenever possible.

But more and more studies are telling us that masks do significantly reduce transmission.

Even if it's not 100%, it's worth doing because it's an easy thing that you can do every day.

And when combined with other strategies, your levels of protection add up.

You know what?

Let's look at some history for a second.

Wearing masks goes back to 17th century plague doctors, who wore special hoods with long beaks that they filled with perfumes, since at the time they believed that sickness was spread by bad odors.

Then in 1905, a doctor named Alice Hamilton published one of the first studies recommending masks after proving that surgeons were passing dangerous bacteria to their patients just by breathing or talking during surgery.

But it wasn't until 1910 during an epidemic of pneumonic plague in China that a doctor named Wu Lien-teh first developed masks to be worn by both medical personnel and the general public in order to prevent the spread of the airborne disease.

And this mask-wearing practice was adopted by many cities during the 1918 influenza pandemic, which is often considered the worst of the modern era.

Masks work, and we've known that for a long time.

OK, I've seen some people claim that there are supposedly mask exemption cards floating around distributed by the "government" saying that you don't have to wear a mask.

That's fake.

Those are all fake.

The U.S. Department of Justice even made an official statement to clear up posts on social media that suggest that they issued exception cards because of the Americans with Disabilities Act.

They did not.

Even if the post has the official DOJ seal, it's not real.

Now, when it comes to masks and disabilities, most local governments have made exceptions for people with legally recognized disabilities.

But even if you meet those requirements legally, it doesn't mean that you can just do whatever you want.

Under the Americans with Disabilities Act, a business can still turn a person away if they are a substantial risk to the health and safety of others.

These potential impacts on disabled people are even more reason that we all have to protect each other.

And just like someone using a fake service dog, using fake exemption cards, well, that hurts people with actual disabilities.

So don't be that person.

And finally, this is one of the biggest misconceptions that I've seen in response to masks and just COVID-19 in general, that COVID-19 isn't a big thing to be afraid of because the death rate is low, or because you're young and COVID-19 is only really dangerous in older people.

This is one of the most dangerous misconceptions going around for a few different reasons.

Now, the death rate of COVID-19 is thankfully low, or at least much better than it could be.

As of this video, across all ages, we see maybe one death for every 200 known infections.

And yes, we do see higher death rates among older people.

But imagine for a second that we take that 0.5% death rate and just let COVID spread across the entire U.S. population.

That would be more than 1.5 million deaths.

And there's really no way to call that good news.

But the other 99.5% of COVID cases are not harmless.

This is a new disease, and we have basically no data on its long-term effects for those with severe or even mild symptoms.

While some people may fully recover, others might have permanent lung scarring, which is backed up by what we saw happen with related diseases like SARS and MERS.

New York and China have seen increased rates in strokes, as high as 1 in 20 cases in some places, and even strokes in younger people.

We are seeing reports of heart damage, pulmonary embolisms in the lungs of as many as a quarter of hospitalized patients, blood clots, and neurological damage, from cognitive impairment to just affecting people's mental health.

Some people, even young people, may never return to living their normal life, even if they recover.

We've seen that this disease kills people under 40, under 30, under 20, and we have incomplete data on how these lingering effects could affect children.

Battling COVID may knock you out for weeks, even months from work, and most people cannot afford that.

This disease is a big deal.

And no matter how young or healthy that you think you are, you are at risk, and not just of dying.

Listen, everyone, including me, including the scientists and the doctors and the nurses out there, wants life to get back to normal.

Unfortunately, you and I cannot go into the lab and make a vaccine come faster.

But there is something that we can do.

Every one of us has the power to make a small difference in stopping this pandemic through simple actions, and one of those is wearing a mask.

Scientific models tell us if 95% of Americans wear masks, then we can save tens of thousands of lives before winter.

This is not a political statement.

The only statement it makes is that you care about those around you, and you want them to care about you.

Stay curious.

And wash your hands while you're at it.