Explainer: Everything you need to know about face masks and the new rules

Melbourne will become a mandatory mask zone on Wednesday at 11:59pm.

The Victorian Government changed its policy on face coverings after it recorded 363 new coronavirus cases on Sunday.

Here's everything you need to know about face mask rules, fines and the four reasons you may not need one.

Are face masks compulsory?

All Victorians in lockdown areas – Melbourne and Mitchell Shire - must wear face masks in public.

When does the new rule begin?

Melbourne and the Mitchell Shire will become mandatory mask zones on Wednesday at 11:59pm.

What constitutes a face mask?

All the usual face masks can be worn, but so can scarves and bandanas, as the state government realises not everyone will have the access or financial means to a factory-made mask.

What happens if I don't wear a mask?

Anyone who does not comply will be hit with a $200 fine unless police are convinced you qualify for one of four reasons.

So what are the four reasons?

1. it may be reasonable not to wear a mask if you are going for a run

2. you have medical issues that make mask wearing difficult

3. you have a job that is not amenable to mask wearing

4. you are a child aged under 12 years old.

But even if you fall into one of those categories you must still carry a mask with you while you are outside.

What are the four reasons I can leave home again?

Going to work or school; Care or care giving; Daily exercise; Buying food and other essentials

I don't get it. Why the change in mask policy?

Masks will help limit the spread of the virus while the threat of community transmission remains high, the government now says. "The evidence has changed," Professor Sharon Lewin from the Doherty Institute told Today. "We actually now know that face masks play a really important role in reducing transmission especially when people are completely asymptomatic."

READ MORE: How to wear a face mask, as Victoria Premier instructs residents to wear them