That seems to be a crucial question as we think about a post locked down Corona virus world.

But the advice appears somewhat confusing.

Do not recommend that the general public Where's Matt?

Task Force recommends wearing cloth face coverings in public public settings.

This is voluntary.

I don't think I'm gonna be doing it.

We know that our frontline doctors, nurses and care workers need them as part of protective equipment to keep them safe and to stop the virus spreading.

But what about the general public in this video?

We're going to see how effective mass are on whether they're crucial to our future.

Let's start with this.

The issue is not clear cut or simple, and yet some think it is.

Look at this image that did the rounds on the Internet.

It shows the number of covert 19 cases in various country, and it suggests that those nations were people wear masks in public have managed to control the virus better.

Now that's a completely floored reading off the graph.

It's a gross simplification.

Of course, those Maher squaring countries is they've been highlighted have all sorts of other measures in place to help control infection.

Experts generally agree that a package of measures are the key to suppressing the spread of Kobe.

19 facemask Don't work alone in order.

Social distancing alone.

Nor does just washing your hands.

And remember that graph points out Japan, which is actually struggling with the Corona virus outbreak.

Japan is the latest country to declare a state of emergency.

Their government was posting masked people only a few weeks ago.

So even though Japan saw the public wearing mouse on Mass, it appears to not have helped.

Indeed, you ultimately can't just take one particular measure amongst many and say, That's the key one.

When you have a multifaceted strategies, i e.

Many different things are happening simultaneously.

You can't actually unpack.

Sat.

Take a recent study published in The Lancet that looked at Hong Kong during Corona virus.

While the authors argue that face Mars for the public should actively be encouraged, they added that they could not identify which measure was potentially the most effective in suppressing the virus, be it facemask border restrictions or testing.

And Tracy, there hasn't been enough research done on face mask to give us a conclusive answer now on whether they would help or not.

So why is there no clear evidence to show math work?

Well, Firstly, it's very difficult to do a randomized controlled trial on face marks wearing in the wider public because of the huge number of variables involved.

I contest a proper surgical mask in the laboratory with doctors and nurses because I can control the setting and the people using the mask know exactly how to use them.

Take that to the wider community and a whole range of issues and to the frame.

What type of mask of all those different people wearing, how often they wearing it?

Are they putting it on right?

Has it been washed properly?

It's very happ acid.

It's very random.

It's very difficult thing.

Many games, the middle of pandemic.

Does that mean people behaved more scrupulously or less scrupulously?

We don't know.

That all makes it very difficult to do.

A controlled experiment with clear results and even those in favor of mass for the public admit we may never get a definitive test.

You can't say to 100 cities nobody in your cities were allowed to use masks and then saying to another 100 cities, everybody in your cities are allowed to use masks during a pandemic.

To do so would be highly unethical.

Secondly, covert 19 is a very new virus, and we're still not 100% sure about how it's transmitted.

For example, the virus could spread through large respiratory droplets when you sneeze or you cough.

Or they could pass through small respiratory droplets.

Like what you admit when you speak what is infectious?

Is it the larger droplets, or is it the smaller aerosol drop ins?

This is a new virus, and we actually don't know the answers to any of those questions.

We actually need to bring together the science off materials at the science off dynamics, and we need to bring together behavioral science.

There's not one bit of science that has the answer to this, so there's no definitive evidence for the use of face masks being worn by the general public.

But there are other concerns about the consequences of asking the public to wear face coverings.

Firstly, there's shortages.

We've all heard stories from the U.

K and elsewhere about the lack of protective personal equipment for healthcare workers on the frontline.

The worry is that that shortage could be exacerbated.

If you tell the public toe wear masks, you need them at every supermarket ready supply of high quality surgical masks, someone showing out what mom properly.

This would be a big, big, big undertaking for uncertain benefits at a time when it gets, and particularly social care and other places they're struggling to get the equipment they need on the concern is that face marks will stop people doing what they've already been practicing.

The idea is that telling people toe wear a face mask will give people a false sense of security.

And it might even make those people who should be staying home venture out into public that people would use it as an excuse not to say surely distance not to stay in there.

Following on.

As countries start issuing guidance and face marks for the public, there's a difference in what they're saying should be warned.

Spain has seen police handout surgical mask on public transport in the United States.

The advice is that even a scarf or a homemade covering will be sufficient.

Some countries are making facemasks mandatory in public.

Others are saying it's advisory that can also send out a mixed message.

It sends that message.

Or maybe they mattered.

Maybe they don't know.

It really, really, really matters that we interrupt transmission of this virus.

It really matters.

And I do think halfhearted attempts that don't send out a good message.

I think they sent out a lack of clarity, and they said now and what it might maxim mind really matches.

Despite the lack of any clear cut evidence, many countries and now encouraging people to wear face masks in public, even Gloria Estefan's getting in on it when you go Out in, helps a world.

So let's start with the argument from the CDC in the United States.

They point out that recent studies show a significant proportion of people with Corona vise lack symptoms and can transmit the virus, and that even those who do eventually develop symptoms conspire ed the virus before they show any signs of having it.

This means that the virus can spread between people interacting in close proximity, for example, coughing, speaking or sneezing, even if those people were not exhibiting symptoms.

In light of this new evidence, CDC recommends in the task force, recommends wearing cloth face coverings in public public settings, where other social distancing measures are difficult to maintain on.

Remember, that means the mask is there mainly to stop you from infecting someone else rather than to protect you from being infected.

But that will only work if everyone on the bus or a train is wearing a mask.

If some aren't and potentially have the virus, that it can still be spread.

That's why some proponents of Marseille it should be mandatory.

While it means it helps everybody if everybody wears one.

So if you go out, you know, on the train and the other passengers on the train or some of them and not wearing a mask.

But you are, and some of them were infected and they're talking and droplets of coming out of their mouth.

They absolutely kind of infect you.

Where else if all the other passengers are wearing a mask, it's pretty unlikely that going to affect you.

The Lancet report into Hong Kong argued that they could be particularly effective in dense cities where Mars wearing is widespread.

We have a very busy city, a lot of people mixing every day on public transport in offices.

There's a lot of crowded areas, and everybody in Hong Kong is wearing masks have 99% mask usage, and I think that contributes.

And those in favor of Public Face Mask countered the argument that people may stop practicing other social distancing measures by asking, Well, what's the evidence for that?

The argument that if we introduced face coverings that people will stop washing their hands that they will start going out and partying and doing all sorts of things that currently they're not doing.

I don't have any evidence to that.

And again, these proponents Do you understand that masts are not a simple solution and that they should be a dear to with other measures we have seen numerous countries around the world changed their guidance on face masks in public.

The most measure we did it cost me.

The Depo Bob searches on the transport public.

So it's all the celulas.

Don't She did make an effort.

You sweat, probably get what a mask go public.

This does not show model thinking more that new evidence is coming out being assessed countries and making their own decisions and they're all not issuing guidance from face mass alone.

But alongside other measures, there are no clear cut answers to how useful face masks are for the wider public.

We're not like healthcare workers who are exposed to the virus 24 7 and that's where the guidance is clear.

They need massed along with other people.

We may never get definitive answers on public face mask due to the variables involved that make a randomized controlled trial really difficult.

As more countries change their guidance, we may get a larger pool of evidence from across the globe to make our thinking a little clearer.

But the common theme will always be that facemask for the public are, but one measure among many it alone is not the solution.