Correctional centre inmates have been evacuated and some students have been advised to stay home as an ominous summer begins in Oberon.
The town has been under an orange glow and smoke from fires in the area for the past week.
The conditions were worst on Wednesday morning, when the air quality was rated as hazardous.
It came after the the Wollondilly fire, south-west of Warragamba Dam, and the Kanangra-Boyd National Park fire combined over the weekend.
The fire, now known as the Green Wattle Creek fire, and which has burnt more than 112,000 hectares, was still out of control on Wednesday.
The bushfire risk in the area led to the evacuation of Oberon Correctional Centre staff and around 120 minimum-security inmates at Shooters Hill on Tuesday afternoon.
A Corrective Services NSW spokeswoman said all evacuees were safe and inmates would be housed at Lithgow and Bathurst correctional centres until further notice.
"We will continue to monitor the situation. Oberon has an on-site Rural Fire Service division," the spokeswoman said.
The Gospers Mountain bushfire, which has been burning in the Lithgow local government area for six weeks, has now grown to more than 320,000 hectares.
An Oberon RFS spokesperson said of major concern in the Oberon local government area is Jenolan Caves Karst, Shooters Hill, Jaunter, Tuglow, Colong Stock Route, Bindook highlands and Gingkin.
Oberon Fire and Rescue put out a call on Facebook on Tuesday inviting businesses and individuals to show their support to Oberon RFS by donating boxes of water and food that can be packed into bags for volunteers to take to the fire ground.
"Even things like wet wipes are a blessing or make a bunch of simple sandwiches," the post said.
An Oberon RFS spokesperson said there were goods left at the doors in the early hours of the morning.
Oberon Public School cancelled swimming lessons on Wednesday due to the air quality and smoke.
Principal Jo'elle Frampton advised parents to keep their children at home if they suffer from asthma or a medical condition that may be affected by the smoke.