National medical stockpiles of particulate-filter masks will be opened up to help authorities on bushfire front lines in Victoria and NSW.
The federal government will also send 100,000 P2 masks to the ACT to help vulnerable people in the capital, Chief Minister Andrew Barr says.
The smoke in Canberra has caused shops, institutions and public facilities to close, with the CBD shopping centre the latest to shut shop on Sunday.
All Qantas flights out of Canberra Airport were cancelled on Sunday, with other airlines still operating.
Qantas apologised to customers and said it was because of the impact of bushfire smoke on air quality for ground staff.
The National Portrait Gallery also closed on Sunday, while the Australian National University campus' have been closed Thursday due to the smoke.
The ACT State Emergency Service has been tasked with delivering P2 masks to stores in Canberra after Australia Post stopped deliveries due to the bushfire smoke over the capital.
The masks have been flying off the shelves in Canberra with the air quality plummeting again on Sunday because of thick smoke from fires outside the ACT.
The capital's air quality was the worst of any major city in the world as of Sunday morning, with some air quality stations returning readings nearly three times above extremely hazardous levels.
The federal government will send 450,000 masks from the national medical stockpile to help Victorian authorities.
It was also working to get masks to NSW frontline workers, having already provided 3000 to Australian Federal Police officers in bushfire affected areas.
Australia's acting chief medical officer Paul Kelly said on Saturday the masks were not an alternative to avoiding smoke.
"The effectiveness of P2 masks to protect against high levels of air pollution is limited and they are not recommended for general community use," Professor Kelly said.
He said anyone with heart or lung problems should consult a doctor before using P2 masks, and anyone who felt dizzy, faint or out of breath while wearing a mask should take it off and get to a place with cleaner air.
Prof Kelly also said the masks were only effective if fitted perfectly and men had to be clean shaven to wear one properly.
Federal Health Minister Greg Hunt said the government was also working with other states and territories to help get masks to frontline workers as required.
Australian Associated Press