In particular, levels of PM 2.5 particles have reached hazardous levels in the Illawarra and Shoalhaven regions on Friday, November 22, long term exposure to PM 2.5 has been linked to respiratory illness and even to dementia risk.

Bureau of Meteorology forecaster Abrar Shabren said smoke haze was expected on and off in the Shoalhaven over the next few days.

"In the last few days a lot of smoke and smoke haze has been driven from the bushfires burning in the north of the state," he said.

"The associated trough is more effective and moving across New South Wales and the frontal system has slipped further south into the Tasman; that created northerly winds which have driven all the smoke from the north into the south - as far as the Shoalhaven and Illawarra."

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The change of winds in the late afternoon today from south to south-easterly will push the smoke further inland but may also bring haze into the area.

"We do have a lot of smoke offshore as well, so the wind will possibly push some of the smoke back onto the Shoalhaven. It will be fluctuating between thick and thin smoke." Mr Shabren said.

"It won't be as thick as it has been for the past few days because of all the wind that is coming it, but there is a high moving in at the end of the weekend which will again create some northerly winds pushing all that smoke again across the region."

NSW Health Director of Environmental Health, Dr Richard Broome said fine smoke particles could become irritating when breathing and also worsen lung and heart conditions.

"For most people, smoke causes mild symptoms like sore eyes, nose and throat. However, people with conditions like asthma, emphysema and angina are more likely to be sensitive to the health effects of smoke.

"People with these conditions should avoid outdoor physical activity when there's smoke around."

Dr Broome advised asthma suffers to carry their puffer on them while haze remained around.