Council of Small Business Australia chief executive Peter Strong said the national work safety watchdog needed to set a national policy on the smoke.

"They need to very quickly get people together, the employer groups and unions, and say 'Right, what do we do here?'," Mr Strong told AAP.

"You don't want to go with a different law in every state."

Mr Strong said businesses need to still be paying out the minimum hours to casual workers if smoke forced their businesses closed.

Maritime union national safety officer Jake Field says workers have an obligation not to put themselves at risk under work safety laws.

Australians also needed access to better real-time air quality data, Mr Field told AAP.

"Prior to December this year ... air quality wasn't really on the community's radar and now it certainly is," he said.

"This is a crisis that we've never faced before in our community, in our country and in our industry."

Mr Field said some stevedores had been forced to work in hazardous smoke and warned workers to be aware of their rights.

Fair Work Australia was contacted for comment but directed AAP to information available on the ombudsman's website, which points to the differing health and safety guidelines in each state and territory.

Safe Work Australia says employees have a right to stop working if they believed their workplace was unsafe because of the smoke.

Workplaces had an obligation to limit their employees exposure to smoke, Safe Work Australia's website says.

During the worst of the smog in Canberra, the home affairs department shut shop and health department staff were sent to other offices.

Australia Post cancelled deliveries in the capital, citing worker safety, and flights at Canberra Airport were cancelled to protect ground staff.

Community and Public Sector Union national secretary Melissa Donnelly said the union was encouraging people to stay home if their offices were unsafe.

"The CPSU have asked agencies to demonstrate that the workplace and air is not hazardous," Ms Donnelly said.

Comcare says there is no Australian standard for acceptable air quality.

Employment law expert Dr Elizabeth Shi said employers could face legal risk by making staff and contractors work in smoky conditions.

"It's unlikely law enforcers will be particularly sympathetic to arguments about cost," Dr Shi wrote in an article for The Conversation.

Australian Associated Press