Sydney, Nov 22 (IANS): A giant dust storm has blanketed communities across southeast Australia turning skies orange and raising concerns about air quality, with authorities issuing a public health alert here on Thursday.

The 500 km-wide dust band has started to reach the city, the BBC reported.

Many regions elsewhere in New South Wales (NSW) have had poor visibility.

Authorities said the storm has been driven by strong winds picking up dry soil. The problem has been exacerbated by a drought that has affected NSW since August, according to Australia's Bureau of Meteorology.

Health officials have urged people to stay indoors, particularly children, older people and those with respiratory problems.

A resident in Broken Hill, a town 1,100km west of Sydney, said the dust had lingered for hours on Wednesday.

"You walked outside and it was in your eyes and it was just a gritty feeling," Matt Whitlum told the BBC.

"The winds were so strong that you had to hold the car door open or it would just slam back into your face."

The Met said it was not yet clear how severely the dust storm would affect Sydney.

A similar intense dust storm had blanketed the city in 2009, leaving hundreds of people suffering from breathing difficulties, and grounding flights.