Largest dust storms in 70 years cover Sydney

Residents from Sydney in New South Wales to Canberra inland and towns in southern Queensland awoke to a red sky and greatly reduced visibility after the country's worst dust storm in 70 years blew in overnight.

The Sydney Harbour Bridge and Opera House were shrouded in the red fog and hundreds of people reported breathing problems to the health authorities.

Children, the elderly and those suffering from asthma or heart or lung diseases were advised to stay indoors as even healthy adults reported "itchy throats" and a metallic aftertaste in their mouths after walking through the thick haze.

Commuters used face masks, originally intended to protect them from the spread of swine flu, to negotiate the clogged streets on their way to work. Some schools were closed and sports activities were called off as the conditions pushed air pollution levels to 1500 times their normal levels – the highest on record.

Passengers at the busy Sydney Airport faced delays of up to six hours for international flights and three hours for domestic trips, and some international flights were cancelled as visibility was reduced to just a few feet.

Sydney ferries were also suspended for several hours for safety reasons.