The territory's air quality has deteriorated to levels worse than much of China with smoke expected to intensify on Sunday night.
Plumes of thick smoke descended on Canberra on Saturday evening as easterly winds carried smoke from bushfires in NSW.
At 8am on Sunday, the air quality was rated "very poor" at Civic and "hazardous" at Monash air quality stations, according to ACT Health.
By 4pm, air quality index had deteriorated to levels worse than parts of China, including major cities like Shanghai.
Shanghai was recording index levels of 162 while Canberra's index was 167.
The smoke haze is likely to intensify tonight when easterly winds return. The haze is expected to continue to impact Canberra in the coming days.
You don’t see this very often. Canberra’s air pollution index (AQI) on par or worse than most of China. Again, shows how good we have it most of the time, and how truly terrible it is in most Chinese cities. #CanberraSmoke#Canberra#Smoke#NSWfires#NSWbushfirespic.twitter.com/NATzHYGjiz— Luke Hennessy (@LSHennessy) December 7, 2019
Bureau of Meteorology forecaster Abrar Shabren said the smoke would be persistent over the coming days.
"We have seen smoke in Canberra from early and late afternoon yesterday and overnight with the fires burning over the south east and east of Canberra," he said.
"Most of the area around ACT and Canberra will see smoke haze lingering for the next few days."
Mr Shabren said winds on late Tuesday could gradually move the smoke.
Public health physician Dr Vanessa Johnston said ACT Health expected air conditions would worsen by Sunday night.
She said people who were sensitive to smoke inhalation should stay indoors with windows and doors closed, avoid vigorous exercise and to go to air-conditioned premises such as a shopping centre or library.
Everyone else should limit strenuous activity outside.
Dr Johnston said small particles within the smoke could be inhaled deep within the lungs and cause coughing and wheezing.
"Particularly for people who have chronic health conditions that can be quite serious," she said.
The smoke haze prompted the ACT Emergency Services Agency to put out a message to assure residents there were no bush or grass fires burning in the ACT. A spokeswoman from the ESA said the agency has fielded 180 calls to triple zero about the haze.
She said those concerned should look to the ESA website as "the single point of truth for all incidents" in the ACT.
It comes as a heatwave is expected to hit Canberra this week. On Monday the temperature is forecast to hit 36 degrees, and on Tuesday 39 degrees.
"There is a bit of a heatwave around the south east of NSW as well as the ACT," said Mr Shabren.
"It will be quite hot and that will elevate fire danger across the ACT as well as parts of NSW."
There is no significant rainfall forecast for the next two weeks in Canberra or at nearby firegrounds.
Both the North Black Range fire and the Currowan fire were at "advice" level on Sunday morning at 9am.
Conditions were expected to ease on the North Black Range fireground on Sunday but will deteriorate as the heatwave descends.
The temperature could get close to 40 degrees in some areas near the North Black Range fire on Tuesday, Mr Shabren said.