As of midnight Sunday, residents returning from greater Sydney, the Central Coast and Wollongong must quarantine in Canberra, as another 15 cases were added to the northern beaches cluster on Monday.

Here are your questions answered about the latest COVID-19 restrictions in the ACT.

More than 30 local government areas across greater Sydney, the Central Coast and Wollongong have been identified in the list of impacted areas. That list can be found here.

The entire Illawarra-Shoalhaven region was initially included in that list but has since been removed. Only the Wollongong LGA remains affected.

ACT Policing is considering implementing a police presence along the Federal Highway to check cars coming back from Sydney are obeying the quarantine directions, but it looks unlikely to be in place on Monday.

ACT Policing said full road blocks were unlikely.

Dr Coleman said two things were different this time. Firstly, there was evidence of "significant community transmission" and seeding outside the northern beaches area.

She was also concerned the cluster's initial case has no identified source.

"NSW are implementing these restrictions in these areas, so they are obviously concerned as well, so we need to mirror that," she told reporters on Sunday.

Dr Coleman has urged ACT residents against any travel to NSW, however there are only restrictions on greater Sydney, the Central Coast and Wollongong.

That means Canberrans can go to the south coast and are currently not required to isolate when they return to the ACT.

However, Dr Coleman has warned the quarantine zones might be expanded as the situation unfolds and advised Canberrans not to travel in the state if they didn't need to.

NSW Deputy Premier John Barilaro has also urged Sydneysiders not to travel to the regions.

Probably not. Health Minister Rachel Stephen-Smith told reporters on Sunday these restrictions would likely remain in place over Christmas and possibly into the new year. Dr Coleman said a final decision would be made in coming days.

No. There is an exemption in the public health direction for people transitting through Sydney Airport.

No. If you travel through the affected areas without stopping you are not required to quarantine in the ACT.

No. If you have completed quarantine and travel directly to the ACT without stopping, you would not be required to quarantine.

There is currently no evidence of virus transmission in the ACT, therefore Dr Coleman said masks were not necessary.

She said people could wear masks in indoor areas where they couldn't physically distance if they felt more comfortable to do so.

There is never any certainty around changing coronavirus restrictions as Health manages the unfolding situation.

Dr Coleman hoped the quarantine requirements would prevent the northern beaches cluster spreading into the ACT and further measures wouldn't be needed.

"I'm really hoping by putting in place this quarantine requirement we can prevent the seeding of cases here because we have quite open [restrictions] ... if we did get a case there would be community transmission," she said.

The latest rules came into effect at midnight, which means if you arrived in the ACT before 11.59pm Sunday from a hotspot you do not need to quarantine.

Dr Coleman said if you aren't in quarantine and don't have symptoms, you do not need to get tested.

However, if you have been in the northern beaches since December 11, you are legally required to quarantine in Canberra and should get tested regardless of symptoms.

"For people who haven't been in those identified areas please don't go and get tested unless you have symptoms," she said.

Anyone with COVID-19 symptoms should get tested.

Yes, but if you are going to drive there you need to apply for a permit. Greater Sydney and the Central Coast are "red zones" and require an exemption to enter but the rest of regional NSW is a "green zone", which means you need a permit and must monitor for symptoms.

The Queensland government will reintroduce a border checkpoint, requiring travellers to have a permit to entre the state. Travellers from a hotspot will be forced to quarantine for 14 days.

ACT residents have not been included in Queensland's restrictions, but it is unclear how Canberra travellers will be affected if they have recently been in NSW.

ACT Health said quarantine was not required unless you had been in one of the local government areas identified.

"However, it is important that we keep the ACT community safe. Canberrans should be avoiding any unnecessary travel in NSW (which includes holidays or festive celebrations) as it increases their risk of contracting COVID-19," ACT Health said.

"Anyone in a COVID-affected area should be discouraged from travelling."

No. You cannot enter the ACT except for transit without stopping until 14-days after leaving an affected area.

If NSW Health allow you to travel, then you can transit through the ACT if it is the most direct route.

Dr Coleman said people must not leave the car or go through any drive-through cafes or restaurants.

Dr Coleman said because the restrictions were not expected to be in place for a long period of time, exemptions were only being considered in "exceptional circumstances".

She said authorities were working with freight and transport sectors to arrange exemptions where required.

"There are some lower levels of essential workers which will become a critical issue the longer we go on for and we will just look at those as we move forward," Dr Coleman said.

According to the ACT Health website, exemptions will be considered for people to leave quarantine under "highly exceptional circumstances" if a person tests negative to COVID-19 and is an unaccompanied minor, requires urgent medical treatment, is a non-ACT resident returning home with permission of their state or in compassionate circumstances.