As Omicron variants of COVID-19 continue to fuel a rise in cases across Australia, there is renewed focus on masks as a simple way to prevent the spread of the virus.
Australia's COVID-19 cases and death rates are now some of the highest in the world per capita, and the numbers are getting worse.
It has led National Cabinet to strongly encourage the wearing of masks indoors, when appropriate, and authorities have warned Australia's current COVID-19 wave will likely peak in August.
So with masks back in focus again, let's take a look at reusing them.
Can you reuse face masks?
The short answer is yes, but how you reuse them depends on the type of mask you're using.
Here is a look at the three main types:
Cloth masks
Cloth masks should be made of at least three layers of "tightly woven, breathable fabric that blocks light when held up to bright light source", according to the Australian Government's Infection Prevention and Control Expert Group (ICEG).
It says cloth masks are reusable, but must be washed after being used.
Surgical masks
The ICEG's official recommendation is that surgical masks not be reused, because they aren't really designed to be reused.
However, many health professionals say members of the public can reuse them a few times if they're not being used in healthcare settings such as hospitals or aged care facilities.
Brett Mitchell, professor of health services research and nursing at Avondale University, says surgical masks can be reused, but like any mask they shouldn't be used if they become dirty, wet or moist in any way.
"That's because it's not providing a barrier any more for airborne pathogens," he says.
"And if you've got the opportunity to perhaps leave them there for a period of time — perhaps a couple of days — so you have a bit of a supply ready to go.
"That will help ensure that the pathogens in there won't survive that long. So that will be fine, just let it dry."
P2 masks (also called N95 masks)
P2 masks, which are also known as N95 masks, offer the best protection from COVID-19.
They are also usually designed for only a single use, but can be reused a few times outside of healthcare settings.
They should be replaced if they become damp, dirty or smelly.
"Sometimes the elastic bands stretch with use, and they don't give you that tight fit that you had the first time you used it.
"So when the elasticity starts to go on the band and you're not feeling that tight fit anymore, that's the time to get a new one and not reuse it anymore.
"When you take them off, try not to stretch the elastic too much."
Do some masks have use-by dates?
Yes.
"You'll probably notice on some boxes of masks they'll have an expiry date — particularly for the P2 and N95 respirators," says Professor Mitchell.
"That's just giving an indication that if you leave them in the box and not use them for a few years, with time things like the elastic band starts to deteriorate and become less effective.
"It's not an indication that you'll be able to continue to reuse it until that expiry date.
"It's more about when we know that those masks still maintain their efficacy if we pull them out of the box for the first time, we know that they're still working up until that expiry date."
Professor Mitchell says the longer you reuse a mask, the higher the risk of it losing its tight fit or becoming dirty or moist in some way, which reduces its effectiveness.
When is a mask considered contaminated?
Masks are considered contaminated once they have been worn, according to the ICEG.
It says you should avoid touching the front of the mask while you are wearing it, and wash your hands or use hand sanitiser if you do.
The ICEG also advises not to store your mask around your arm or wrist, or pull it down to rest over your chin or neck.
Masks which have been worn shouldn't be shared with anyone else, either.
"That's why I also recommend leaving that mask for a day or two to dry out, so there's a chance for those pathogens such as SARS-CoV-2 to die."
How often should you wash a cloth mask? And how?
After you've used a cloth mask, you should put it in a clean plastic resealable bag until it can be washed, the ICEG advises.
The mask should be washed each day it's used, at a minimum.
Australia's national public health information service, Healthdirect, says cloth masks should be washed using soap or detergent, preferably in hot water. Or they can be put in the washing machine with other clothes.
When drying them, it's recommended to let them air dry in direct sunlight, or use a dryer if you need to.
"You may choose to launder it, or you may choose to just the leave mask to dry for a day or two, and that's completely fine.
"But there probably comes a time when you go, 'I think it's a bit smelly, let's wash it and leave it to dry'.'"
What's the life span of a cloth mask?
The life span of a mask depends on how the mask is made, and how much it's used.
"It's really difficult, because it's so variable," says Professor Mitchell.
"There's no set standards on cloth masks to give an idea about how many times you might be able to use it.
"But when you think that the mask is no longer giving you the best fit that it did when you first used it, that's time to think about either changing the loops or elastic bands on them, or getting another one."
