Hazard reduction burns across Sydney have been suspended for at least 24 hours to allow smoke from earlier burns to clear, with agencies considering whether to go ahead with a planned burn near Wollongong.
The NSW Office of Environment and Heritage dropped the air quality rating in the harbour city to "poor" for a second day on Wednesday, with Sydneysiders again waking up to hazy conditions and a sharp smell of smoke.
The NSW Rural Fire Service wrapped up burn-offs in the Blue Mountains National Park on Tuesday afternoon but residual smoke remained on Wednesday afternoon.
NSW RFS said on Wednesday all burns within the greater Sydney region that would affect smoke haze across the basin, had been postponed for 24 hours.
RFS spokesman Greg Allan said while smoke from the Blue Mountains fire may affect the Sydney basin, no new direct fires were planned in that region on Thursday.
Agencies were considering whether to go ahead with a planned burn near the upper Avon area, west of Wollongong, on Thursday.
"We're taking into account again the winds, the amount of smoke that's already in the area and if any smoke from this burn, should it light up, will in fact affect the greater Sydney region or Wollongong to a great extent," Mr Allan told AAP.
RFS will continue to speak with partner agencies including NSW Health and the NSW Bureau of Meteorology to see when, if possible, it can "take advantage of the conditions to do this important work".
A decision is expected early Thursday evening.
The haze had already started to thin on Wednesday afternoon, according to NSW Bureau of Meteorology forecaster Stephen Stefanac.
A wind change over Sydney's east should see most of the smoke pushed inland, mostly towards the western suburbs, he told AAP.
"Generally across the Sydney basin there will still be a little bit of haze in the east this evening, but not as bad as it was this morning," Mr Stefanac said.
NSW Health warned on Tuesday the smoky conditions could irritate the respiratory system and aggravate existing lung and heart conditions.
The advice remains in place for Wednesday.
People with asthma, emphysema and angina are more likely to be sensitive to the effects of smoke, environmental health director Richard Broome said in a statement.
Vulnerable people are advised to stay indoors, close windows and avoid vigorous exercise.
Australian Associated Press