I saw these images circulating around the internet that

showed bacterial cultures growing in Petri dishes

and claiming to represent the effectiveness of masks

in stopping or minimizing the spread of germs.

It was in relation to COVID-19 and whether or not

we should all be wearing masks.

So today we're gonna recreate this experiment and

document it to see how accurate it was and whether or not

our mask results come out the same.

- Now we trace the images back to the Twitter user,

Dr. Rich Davis, love that very expensive name,

he is a director of a microbiology lab,

so yes, his results seem VV legit,

but we want to reproduce his demonstration on our own

for a few reasons.

One, because it's an excuse to do some fun at home science,

and maybe we'll have some new friends in quarantine,

aka these bacterial cultures.

Two we wanna see if our results will be consistent.

- Three, we really wanna test homemade masks

because the ones in the pictures look like surgical mask,

but I feel like a lot of people just made their own at home,

like these ones, my mom made that are super cool.

She just basically put two layers of cotton fabric together

and some elastics on them.

Mom, you did an amazing job,

I feel like a science superhero walking down the street.

So yeah, there's a whole bunch of them,

should she start a line?

Now, just before we start,

I know some of you might be screaming at your screen saying,

but Mitch Coronavirus is a virus, not a bacteria.

And that's totally true,

so let us explain why this experiment is still relevant.

- Right now scientists believe that the main mechanism

of transmission for SARS CoV-2 virus

is through respiratory droplets.

The virus doesn't just float around,

it relies on moisture from an infected person to trap.

And given that bacteria from the mouth, nose and throat

travel in the same way, while these dishes aren't gonna

show us how much SARS CoV-2 virus is on them,

it will show us the relative amount of droplets.

And these droplets by proxy are telling us how our germs

spread, whether we're wearing a mask or not wearing a mask.

- As an added bonus, I actually got some friends

who work in a lab at the University of Toronto,

who are also going to recreate this experiment

with us at the same time, but under even more ideal

conditions for the bacteria to grow,

which we'll get to in a bit.

Ultimately, all this is to test and figure out

how well masks work.

Okay, so we are here with our agar plates,

I've got gloves on, these have been sterilized,

we actually got them from our friend, Amanda

who works in a lab who was able to prep these

in a proper autoclave, and we've sterilized this countertop

and we're trying to be super careful because we only wanna

see what's actually coming out of my mouth.

- [Narrator] Hot. - Hot.

These are called LB plates.

Basically it means that the agar that's in them

is going to help the bacteria thrive.

There's other kinds that help fungus thrive,

but in this case, we wanna see the bacteria come up

cause that's mostly what's gonna come out of my mouth.

- [Narrator] Once we had all the plates ready to go,

we began the experiment.

We held each plate around 1.5 feet away from the face

and coughed twice on one, (coughs)

sneezed twice on one, (sneezes)

a fake sneeze had to suffice, talked for one minute to one.

- There's hydrogen and helium then lithium, beryllium.

- And sung for one minute to one.

♪ There's hydrogen and helium then lithium, beryllium. ♪

- Finally, we then repeated all of these activities

with a mask on. (coughs then sneezes)

- This is the periodic table

♪ The noble gas is stable ♪

Now that we have all our samples done,

we're gonna keep them in this room

which is the warmest room in our house,

I'm literally like sweating right now.

All the bacteria, eats up all that agar goodness and grows,

and then we'll just come back and check on them soon.

- [Narrator] One week later.

- Now because we don't have an incubator in our home,

obviously, our samples will grow pretty slowly,

so I enlisted the help of some friends who work at the

Molecular Genetics Department at the University of Toronto

who are going to duplicate this experiment

under even more ideal conditions.

Of course, because of COVID-19,

we weren't allowed to go in the lab,

so they're gonna walk me through the important

differences right now.

- At the lab, we've used Brucella Blood Agar plates.

Brucella is a type of media and it's supplemented

with sheep's blood, heme and vitamin K,

and these are additional nutrients that a lot of organisms

in the microbiota need to grow.

- That won't necessarily change the result,

it will just help to amplify any of the bacteria

that are actually coming out of me, right?

- Absolutely, we would expect to see the exact same results

at home as in the lab,

except we might be seeing different species of bacteria

growing on our home plates than we are in lab,

and in the lab we're giving them a lot more nutrients

and a lot more conditions to help them grow even better.

- Also in the lab I know that or using an incubator,

why is an incubator useful and what does it actually do?

- So we typically grow bacteria in a 37-degree incubator,

and this is because our bodies hover around 37 degrees,

assuming you have no fever.

And so any microbe that grows inside the body

grow the best at 37 degrees.

- What do we actually expect to grow on these plates

and is any of it dangerous?

- In general what you're going to see is just

the commensal, normal everyday bacteria and fungi

that you have within us.

And we need them, they provide us our nutrients,

they help us digest our food,

they help protect us against other bacteria and fungi

that are trying to cause us harm.

Most of them are really helpful and also friendly.

- Yeah, they're our friends.

That's really cute, it's nice to know that.

- One other big thing to remember is that

we actually can't see viruses growing on plates in a lab

or even at home, and that's just because viruses

are so small.

So while this experiment is a great experiment at giving

a snapshot of what could be in your droplets,

this will not include any kinds of viruses and it's not

gonna include any types of bacteria or fungi

that can't grow in the conditions we provided them in.

So it's always gonna be an underestimation.

- This is the most important question,

what will you be singing to your Petri dishes?

- I thought long and hard about this,

and I've decided to go with the classic karaoke song,

Uptown Girls.

- Yes.

- [Narrator] Three days later.

- As if we ever would say it like that.

(both laughing)

- Alright, so we are ready to look at our results, we have..

- Say hello to our new little friends, to our roommates.

- Our plates have been growing for over a week,

maybe almost two now. - I think it's two weeks now.

- Whereas the laboratory plates are only gonna

have been two days.

All right, shall we start with coughing?

The Petri dish for coughing, there's no colonies on the mask

Petri dish and there's one big chunker chunker

on the no-mask Petri dish.

- And maybe another little one over there

but yeah. - Yeah,

with the lab results, we see no bacterial cultures

when coughing with a mask, and coughing without a mask,

we see one sort of smacked up in the middle,

really good aim.

Coughing, we weren't sick, we had a dry cough.

I remember while doing it being like,

is on anything coming out?

- So the sneezing Petri dishes are where we saw

the most difference.

So again, the masked sneeze showed nothing on Petri dish,

but the unmasked sneeze is out absolutely covered.

There's probably, I don't know, 50 little colonies growing?

- Hmm.

- Wow, I mean, obviously this is why,

even when there's not a global pandemic,

you sneeze into your arm.

Why when people sneeze on the subway you have a good reason

to be like, what?

- Cover your mouth.

And it's just so much.

I'm so surprised as that nothing seemingly made it through

on the masked one and yet so much made it through

without a mask.

The lab results were also interesting,

no cultures when you had a mask on with sneezing,

but then without the mask tons all over the plate.

- The plates from talking, we see without a mask,

there are about eight,

there's quite a few colonies growing,

with the mask, there are none.

So I think this is really striking because talking is

something that we are all doing.

Lab results show talking with the mask,

no bacterial cultures and talking without a mask, a lot.

- Yeah, I know it's actually surprising,

maybe almost as much as the sneezing in this case.

- This is why it's so important that you have a mask on.

- It probably depends how much enunciating we were doing.

- I was reading a study where they actually analyzed

using computers and like lasers, how many droplets

were coming out of people's mouths as they spoke,

and they got them to say stay healthy because the T-H noise

is known to create a lot of droplets.

I think the T-H noise yeah.

- So singing we're seeing nothing on the masked version,

and we're actually seeing quite a few drops on the no mask.

Do not sing without a mask right now people.

It's pretty, it's kind of staggering, there's probably

six to eight colonies starting, some of them big.

And this makes sense when you hear about how choirs

were spreading COVID and how they've shut down Broadway

for good reason.

- Finally, in the lab with singing nothing with the mask

and a lot without a mask.

So I'd be curious to see what would happen if this had

a full week like ours, it could

probably cover the whole plate.

So these plates are helping us to understand how much is

coming out of us and the effectiveness of masks in stopping

those droplets and not necessarily how effective the mask is

in protecting you.

So that's just something to take in mind.

- Yeah, wearing a mask is altruistic,

it's about you protecting other people around you,

which I think is kind of a beautiful thing.

I'm wearing this mask

for other people. - For other people.

And I also just wanna say that masks are potentially part

of the solution, but they're not the whole solution.

- Yeah. - So, we should be very masks,

we should be washing our hands,

- Physically distancing. - Yeah.

Isolating completely if you've ever been exposed.

And then obviously we're all hoping that vaccines

and treatments come together.

And that is kind of like a holistic look at how we can all

be working together to stop the spread of this virus.