The lingering haze was the result of a series of controlled hazard reduction burns carried out across Greater Sydney, the Southern Highlands, Blue Mountains and the northern Illawarra this week.

Westerly winds first pushed the smoke over Wollongong on Monday afternoon. It then settled overnight and hung around for much of Tuesday morning. 

Despite the lingering irritant, the region’s air quality monitors reported ‘good’ conditions to start the day.  

Light showers that fell across the Wollongong CBD about 9am helped to diffuse the smoke, briefly, before conditions deteriorated late morning.

The air quality index was in the ‘poor’ zone between 11am and 1pm, but had returned to ‘good’ by early afternoon.

Multiple agencies were responsible for the hazard reduction burns – including the Rural Fire Service, Fire and Rescue NSW, NSW National Parks and Wildlife Service and the Sydney Catchment Authority.

Read more: ‘Prepare now’: RFS warns of high fire risk

This week’s hazard reductions were part of extensive back-burning operations, planned ahead of what experts say could be an early start to the fire season. 

“These are important controlled burns which will reduce the risk to people and properties from bush fires,” the RFS said. 

Ross Bradstock, director of the University of Wollongong’s Centre for Environmental Risk Management of Bushfires, told Fairfax Media this week that rapidly drying out vegetation had raised the risk of early and significant fire activity.

*planned hazard reductions from August 12-18.

Illawarra asthma sufferers are being warned to take precautions as burn-offs leave a smoky haze across the region.

Illawarra Shoalhaven Local Health District director respiratory medicine Dr Graham Hart said residents with certain conditions, as well as those with current infections, would be feeling the effects.

‘’Patients with long-standing lung problems such as asthma or chronic obstructive pulmonary disease (COPD) – even patients with heart failure who have respiratory problems – would be experiencing problems with the air pollution,’’ he said.

‘’The smoke haze would also be an added burden to the many people currently suffering from current respiratory infections.’’

Dr Hart said symptoms included chest tightness, a worsening ‘wheeze’ and increasing shortness of breath.

‘’Now is a good time for people to review their action plan for asthma or COPD,’’ he said.

‘’They need to carry their reliever medication around with them, and if they’re deteriorating then they need to come to hospital.’’