As of now, Victorians cannot leave their homes without wearing a mask.

Unless they want to cop a $200 fine. Or have an exemption.

Premier Daniel Andrews says masks or face coverings will be mandatory for people who leave their homes for the four legal reasons in metropolitan Melbourne and in the Mitchell Shire from 11.59pm on Wednesday, but there are some masks that are better than others.

The N95 masks, which protect against at least 95 per cent of very small particles, have become the gold standard for mask protection.

But the valve variant is under scrutiny for everyday use.

A N95 respiratory mask with an air filtering valve. Photo: Getty

These masks have a one-way valve allowing exhaled air to pass through a small round or square filter disc attached to the front.

Valve masks have several benefits.

In addition to protecting the wearer if fitted correctly, they allow easier exhalation than traditional masks, prevent humidity and reduce uncomfortable heat and carbon dioxide buildup inside the mask.

Even though valve masks adequately protect the wearer, they fall short because of the valve design that only filters air breathed in, but not breathed out.

“What we’re worried about, especially when people cough, is that it’s more likely to cause a spread,” Mayo Clinic nurse manager Paul Albrecht said to News8000.

“It’s forcing and jetting (particles) out through the openings, so it might actually be pushing it a little further than it would typically.”

Victoria has mandated the use of masks, but the NSW government won’t implement similar rules despite the growing COVID-19 caseload.

“What NSW Health and myself are worried about most at this moment in time is what people are doing when they’re entering hospitality venues … You can’t wear a mask when you’re having a meal,” Ms Berejiklian told 2GB radio.

“That’s where the biggest risk is at the moment, indoor events.”

In Queensland, Australia’s peak medical body says Queenslanders should consider wearing face masks in public even though the state’s rate of COVID-19 infection is almost at a standstill.

There are just three active cases across the state, with one new positive test on Wednesday that was acquired overseas.

Australian Medical Association vice president Dr Chris Zappala said there was strong evidence masks could reduce community transmission, and that early adoption of the accessories could prevent Queensland from fresh outbreaks like those seen in Victoria and NSW.

“We must remain vigilant and regard this virus, even in Queensland, where we’ve only got a couple of active cases, as poised and ready to infect us,” he told ABC radio on Wednesday.