Air quality above 200 is considered 'hazardous' and the current rating for the region remains the worst in NSW.

AIR quality in the Central Tablelands has reached its most hazardous for this week.

On Friday morning the air quality rating was 1588, which is significantly higher than the hazardous rating on the NSW Department of Planning, Industry and Environment (DPIE) website.

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

READ MORE: PM Scott Morrison cancels leave after fire deaths

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.

READ MORE: Shock, sadness after firefighter death

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.

READ MORE: Heatwave crest hits most of Australia

Why not subscribe, the first 30 days of full website access is free.