We're staying at home and washing our hands, but should we wear a face mask when we go to the supermarket?

This is a common question from the ABC audience, while YouTube is awash in DIY-mask videos and the subject has become a focus for misinformation and even conspiracy theories online.

We'll try to sort fact from fiction and provide some practical advice about face masks in Australia.

Have we been ordered to wear masks in Australia?

While some social media posts claim otherwise, at this point the Australian Government has not recommended all Australians wear face masks

The official advice remains that you only need to wear a mask if you are sick with COVID-19 symptoms, or if you are looking after someone who may have COVID-19.

If you are well, according to the Department of Health, you do not need to wear a face mask.

The most effective way to protect yourself and others against COVID-19 is to frequently and thoroughly wash your hands, cover your coughs and sneezes, and maintain a distance of at least 1.5 metres from others.

Misinformation about facemasks has been circulating on social media. ( ABC News: Supplied )

What do masks do?

Face masks are used primarily by people in the community to prevent sick people from spreading infection.

COVID-19 is mostly spread via respiratory droplets — the little secretions we generate when we sneeze or cough — and face masks can help to catch some of these fluid splashes.

The US Centers for Disease Control and Prevention recently updated its guidelines to recommend all Americans wear cloth or fabric face coverings when they're in a public place.

This is to reduce the spread of infection by asymptomatic people (meaning they're sick with COVID-19 but show no symptoms), according to Abrar Chughtai, an infectious disease epidemiologist at the University of New South Wales.

"Those asymptomatic cases can transmit infection, so due to that reason, the CDC is recommending everyone use masks, because … we don't know who is sick and who is healthy," Dr Chughtai said.

While there are likely to be asymptomatic cases in Australia, Dr Chughtai said community transmission levels were still "very low" (especially compared to the US), meaning widespread face mask use isn't necessary.

"If the number of cases surge here at some stage, like in the US or China, probably then the Australian Government would also recommend everyone use masks," he said.

On YouTube, facemask DIY tutorials are booming. ( ABC News: YouTube screenshot )

Is wearing a mask enough to protect me against COVID-19?

No.

Associate professor Craig Lockwood at the University of Adelaide's Joanna Briggs Institute said if people in the community did wear face masks, they must think of "masks, plus".

Research shows protection from COVID-19 requires social distancing and practising regular hand hygiene.

Not to mention, you need a mask that fits, that provides good filtration, and you must know how to take it on and off without accidental contamination.

How to remove it only touching the mask's strings, for example, and remember to wash your hands before putting it on and after taking it off.

"If people just wear a mask and think 'ok I'm alright now, I'm wearing a mask', they're wrong," he said.

Is any mask a good mask?

Not all masks are created equal.

To begin with, there are two main types of medical-grade masks: surgical masks and respirators.

Surgical masks — the ones you typically see in public — are disposable and loose-fitting, and create a physical barrier between the mouth of the wearer and their immediate environment.

They also help to protect the wearer against large droplets and splashes of fluid from others.

Respirators (such as the P2 masks recommended for bushfire smoke) also protect against large droplets, however, they reduce the wearer's exposure to much smaller particles, including aerosols.

To effectively wear any kind of mask, it must fit snug around the face and mouth, Dr Lockwood said.

The disposable surgical masks available at pharmacies may have good filtration properties, but they are unlikely to fit tightly like a respirator.

The material structure of a mask is also a factor in its effectiveness. A proper surgical face mask has a multi-layered barrier, for example.

Dr Lockwood described it as a "three-dimensional maze" that airborne particles must weave through before they can reach the nose or mouth.

Homemade masks are not tested or standardised, so may not have that same structure.

But Dr Chughtai said cloth masks could be a solution in countries where supplies of medical grade masks had to be reserved for healthcare workers.

"Cloth masks provide less protection compared to medical masks, but they still provide some protection," he said.

Is it OK to make a mask at home?

Many ABC readers have asked whether they should make masks at home, but it's not so simple.

As mentioned above, surgical masks have a maze-like structure that may be difficult for people to recreate.

A doubled-over tea towel could provide filtration, for example, but it would also be hard to breathe through.

"You have to breathe in and out harder, and that causes more air flow around the sides of a homemade mask," Dr Lockwood said.

After all, one major problem with homemade masks is the fit.

The benefit of a N95 mask is not just its filtration, but how closely it hugs the face.

"It's got a good seal all the way around the mouth and nose, and that's the extra bit that makes it effective compared to a homemade mask," he said.

And while a DIY cloth mask may provide some filtration, it may not prevent the accumulation of moisture.

"Once it becomes permeable due to moisture, it loses a lot of its effectiveness," Dr Lockwood said.

When it comes to fashioning face masks out of fabrics, Dr Chughtai said cotton blends (like cotton–polyester) are probably better than pure cotton.

But, he said, they have to be used very carefully, changed frequently (after single use or whenever they got wet), and ideally made out of multi-layered, non-porous fabrics.

Does washing a mask work?

Spraying the outside of a surgical mask with disinfectant may reduce its protective properties and make it less effective, Dr Lockwood said.

"Surgical masks are designed to be hydrophobic or repel liquid."

Cloth or homemade masks need to be washed after every use, Dr Chughtai said.

"Don't touch the outer surface of the mask, remove the mask from the strings, and then put it in a bag before cleaning, or directly put it into the laundry," he added.

Can you clean masks? Not without the right tools. ( ABC News: Supplied )

Can single-use masks be 'quarantined' and reused?

A lot of protective medical wear is designed to be disposable.

Even six hours is considered an extended lifespan for a surgical mask, according to Dr Lockwood.

"As soon as someone touches the outside of their mask, then their hands are contaminated as well," he said.

As for quarantining, there is no evidence putting a mask in a cupboard for 14 days would eradicate the presence of the virus.

"The virus seems to be able to survive quite well on different fabrics for seven or more days, and that end point is not yet fully known," Dr Lockwood said.

Are we being told to not wear masks to keep them for medical workers?

There is currently a worldwide shortage of face masks, and in Australia, healthcare workers are under increasing pressure due to limited supplies.

It is important medical-grade masks and other personal protective equipment are preserved for healthcare workers who face a much higher risk of being exposed to COVID-19 and becoming ill.

However, limited supplies are not the only reason healthy members of the general public are not advised to wear masks, according to the WHO.

WHO's epidemic chief Mike Ryan recently said there was no specific evidence to suggest that the wearing of masks by the general population has any particular benefit.

"In fact, there's some evidence to suggest the opposite," he said, noting there are risks posed by improperly fitted masks or improperly putting one on or taking one off.