There's a lot of choice about what type toe wear.

And in some countries the advice is changing as we learn more about how the virus spreads.

So what are the options?

Well, ah, home made face covering is the simplest and cheapest, and it was promoted in 2020 because of worries about shortages of professional masks that medics desperately needed.

This one.

It's made from an old T shirt.

It's got three layers.

So should do a reasonable job of stopping any virus that I might release.

Which really matters because upto one in three people may be infected without even realizing and to make it more effective.

There's the idea of doubling up having to coverings one on top of the other because that gives you more layers to stop the virus getting through.

We saw a lot of these double masks on Inauguration Day in Washington.

They're not recommended by the US government or by the World Health Organization, but they are catching on.

Next up in quality is the surgical mask, thes air water resistant.

So if someone coughs right at you.

The virus should be blocked.

They should provide you with some good protection on others around you, but they don't fit very well.

There are gaps at the sides that tiny virus particles called aerosols could get through.

You can see how that happens in these lab tests.

They show how air Andi aerosols can escape from around the masks.

So to guard against that, there are better grades of mask.

They're called N 95 in the US or F F P two or F F P three in the UK They've got filters inside them to screen out those aerosols in Austria there now required on Busses and in other public areas, while in Germany, elderly people have been given them for going shopping.

Thes have a much closer fit, no gaps, which means you should be safer.

But they are a lot more expensive.

While home made coverings air basically free, surgical masks cost about 10 pence each, while the FFB, to cost about £3 on their own masks, are not going to defeat the pandemic.

No one is claiming that, but research shows they can make a difference.

Look how far a cough goes when there's no face covering to stop it, so anything that helps is worth pursuing.

But they've got to be worn and removed really carefully, and they're bound to be with us for some time to come.