"The reason for the dust is we had some really strong winds in the inland areas of NSW and in South Australia for a sustained period yesterday," she said. "That's lifted a whole lot of dust off the ground because it's quite dry out there, many of those areas are still drought affected." ----------------------------------------------------------------------------------

MULTIMEDIA: Dramatic photos of Sydney cloaked in red haze

---------------------------------------------------------------------------------- The lifted dust had been carried by the winds into Sydney. "I've not seen anything like this before," Ms Golding said.

The reddish haze was expected to fade as the sun got higher in the sky, Ms Golding said. The haze had turned from a crimson red to orange by about 7am, and then faded to yellow by about 7.30am. But it was not known what would happen to the dust. "This is such an infrequent event ... it's hard to say when the dust will stop." It's just red, red, red as far as you can see

The dust has caused havoc with the city's transport system this morning, with visibility on the roads reduced to just a few hundred metres in some places. All citybound lanes on the M5 East tunnel were closed earlier this morning because of dust in the tunnel. The RTA also urged drivers across the state to exercise caution and reduce speed due to "significant dust over the city affecting visibility". International and domestic flights at Sydney Airport were delayed as a result of the "strong winds and dust haze", a spokesman said. A number of incoming international flights had been diverted to Melbourne and Brisbane, although some flights had managed to land in Sydney, he said.

While delays were expected throughout the day, the airport was not closed, contrary to some reports, he said. Sydney's ferries were also suspended due to poor visibility on harbour. Emergency services had also been stretched by the conditions. The Ambulance Service said it had experienced an increase in calls from asthma sufferers as a result of the dust haze this morning. Some were taken to hospital, a spokeswoman said.

The Fire Brigade received over 500 calls between 3am and 7am, triggered by automatic fire alarms. It normally received only 30 a day in that time period. "This is one for the books," a spokesman said. "A lot of fire alarms are particle-type alarms and the dust gets in and sets them off. "We are flat strap at the moment ... there's going to be a high flow of fire brigade traffic through the metropolitan area today."

The Bureau of Meteorology has issued a severe weather warning across the state because of widespread damaging winds, which are expected to increase in force across Sydney this morning. "It's been close to 60km/h already this morning ... it's just a matter of time before it gets stronger," Ms Golding said. Wind speeds this morning were expected to average over 65km/h, but there would be gusts in excess of 100 km/h, the Bureau said. The winds would gradually ease over the afternoon and evening, Ms Golding said.

The winds were being whipped up by a cold front that passed through the state yesterday, and a deep low pressure trough over Victoria. Temperatures this morning in the low 20s, and were expected to remain that way for the rest of the day, Ms Golding said. Last night, large hailstones fell in parts of Goulburn and Wagga, while wind gusts exceeded 90km/h, the Bureau said. A 109km/h gust was reported at Moss Vale, it said. The State Emergency Service of NSW received about 175 calls for help from residents of Crookwell, near Goulburn, as a result of fallen trees and damaged roofs, a spokeswoman said. Despite the sun rising at 5.43am, the city was still a dark orange haze at 7am this morning.

Many residents took to social networking sites, with Sydney one of the top 10 topics on Twitter this morning. Loading Public schools across the state were open, an Education Department spokesman said. "But given the circumstances if parents are concerned about the effects of the high levels of dust in the air and if their children suffer from asthma or other breathing problems then they can keep their children at home," he said.