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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.
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