Many stores at Stockland Shellharbour (which recently ended up on the NSW Health alert list) had signs up to ask shoppers to wear a mask for the safety of the public, although not mandated.

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Shellharbour Mayor Marianne Saliba said she has always urged the community to do their bit by sanitising, wear a mask and social distance, but her city's track record defends the state government decision not to enforce it in the city.

"In Shellharbour there still has been no positive tested people at this stage," Cr Saliba said.

"[Having different rules for Wollongong and Shellharbour] does create a bit of anxiety and a bit of uncertainty, but I don't think it actually makes us anymore unsafe.

"We need to make sure we're doing the right thing and not provide an opportunity to spread this virus."

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She said businesses outside Wollongong who were choosing to ask patrons to wear a mask should ease confusion with signage and information on their social media pages and websites.

From Monday, on-the-spot fines can be given to people not wearing masks at settings in Wollongong like cinemas and theatres, hair salons, public transport, tattoo parlours and supermarkets.

On the north side of Windang Bridge, owner of the Gala Cinema at Warrawong, Ian Hyslop, welcomed the mask mandate and said it should have been brought in "ages ago".

"I was hoping the masks would have been mandatory for everyone from beginning of December - because of Christmas parties - to stop the spread of COVID-19 prior to the holidays but it didn't happen that way," he said.

"I'd like to see it extended down to Gerroa ... people live at Kiama and shop at Wollongong or come up to Warrawong and vice versa."

Mr Hyslop didn't think it would deter people from heading to the cinema, as some his older patrons had already been wearing masks since they reopened post-lockdown.

"Maybe [it might deter some] but we've noticed a lot of the older patrons that we do get have been wearing masks since we reopened," he said.

For a full list of where it's mandatory to wear a mask, visit the NSW Health website - https://www.health.nsw.gov.au/Infectious/covid-19/Pages/public-health-orders.aspx#face-coverings