Image copyrightMATT WHITLUMImage caption The outback town of Broken Hill was hit by the dust storm on Wednesday A giant dust storm has blanketed communities across south-east Australia, turning skies orange and raising concerns about air quality.Authorities issued a public health alert for Sydney on Thursday as the 500km-wide (310 miles) dust band began to reach the city.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 the entire state of NSW since August, according to Australia's Bureau of Meteorology.Image copyrightMATT WHITLUMImage caption The dust storm has already affected many regions of New South Wales Health officials have urged locals to stay indoors, particularly children, older people and those with respiratory problems.One 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 TheIndianSubcontinent."The winds were also so strong that you had to hold the car door open or it would just slam back into your face."Forecasters say it is not yet clear how severely the dust storm will affect Sydney.However, it has already drawn comparisons to an intense dust storm which blanketed the city in 2009.

Image copyrightGetty ImagesImage caption The 2009 dust storm seen above the Sydney Opera House That event left hundreds of people suffering from breathing difficulties, and forced the grounding of flights.