NSW has succumbed to the highest levels of air pollution from smoke ever recorded, as Sydneysiders wake to air quality conditions worse than Shenzhen, China. Some of the smoke is reaching as far away as South America.

Air quality in the harbour city was ranked ninth poorest in the world on Friday when compared with other cities, with the visibility index at every suburban monitoring station reaching "hazardous" levels, thanks to the state's unrelenting drought and intense bushfire season.

The Environment, Energy and Science unit of the NSW government said the past two months "have been the dustiest on record".

"The impacts of the severe and ongoing drought have led to the highest levels of dust recorded in NSW since our rural air quality monitoring networks began during the millennium drought," a spokeswoman for the unit said.