Sydneysiders may have to put up with a smoke haze triggered by an out-of-control bushfire in northern NSW for a number of days.
The fire, burning in the area of Lake Innes and Lake Cathie, south of Port Macquarie, had scorched 1700 hectares by Wednesday morning and was continuing to spread.
The blaze, which has been burning for several days, broke containment lines earlier on Tuesday, the NSW Rural Fire Service said in a statement.
"Firefighters and aircraft have been working to slow the spread of the fire and protect properties," NSW RFS said.
"Large air tankers have been used to drop retardant close to homes in an effort to slow the fire."
The fire triggered an emergency warning on Tuesday, but early on Wednesday had been downgraded to advice level as conditions eased.
"Firefighters will be conducting backburning operations where local conditions allow today," the RFS said.
"You will see an increase in smoke and flames while these operations are carried out."
Residents in Lake Cathie, Long Point, Bonny Hills, Kew, Kendall, Herons Creek and Bobs Creek were warned to monitor conditions.
Inspector Ben Shepherd said a smoke haze over Newcastle, Sydney and the Illawarra was from "fires up towards the Port Macquarie region".
"Most of the smoke is drifting down under very strong north-northeasterly winds," he said.
"The winds are particularly strong and will continue throughout the afternoon so we are likely to see the smoke hanging around Sydney for some time."
The RFS subsequently warned the smoke was expected to settle "and may continue for the next few days".
NSW Health reminded people that children, older adults and people with heart and lung conditions were most susceptible to the effects of air pollution and excessive smoke.
There were 71 fires burning across NSW as of Wednesday morning, with 30 yet to be contained.
Much of state's southeast will be under very high fire danger for Wednesday.
This includes the greater Hunter, greater Sydney, Illawarra/Shoalhaven, Monaro alpine, Southern Ranges and Central Ranges fire areas.
Parts of the state's northeast and southeast will also be under a high fire danger rating.
Australian Associated Press