On Friday morning the Air Quality Index rated Orange's air at 1588, which is significantly higher than the hazardous rating on the NSW Department of Planning, Industry and Environment (DPIE) website.

Swimming will continue as usual in the centre's indoor pool but the Orange City Council statement said the decision to close its 50-metre outdoor pool was based on the potential impact for pool staff working outdoors in such conditions.

The statement says the outdoor pool "can reopen once conditions improve".

This is the most hazardous it has been this week, and is currently by far the highest rating in NSW.

Massive out-of-control bushfires continue to produce large volumes of smoke, with winds pushing this across the region.

The Gospers Mountain fire, burning within one kilometre of a Central West jail and power plant, has grown to 444,905 hectares and remains out-of-control.

While the 167,907 hectare Green Wattle Creek fire in this region, currently burning at emergency warning level, was the location where two volunteer firefighters died overnight.

At the current hazardous air quality level, DPIE said everyone, especially people with heart or lung disease, should avoid outdoor exertion and stay inside as much as possible.

"If you have symptoms rest and use your reliever medicine," the warning states.

"If symptoms persist, seek medical advice."

Stay up-to-date with fires in your area at Fires Near Me.