SYDNEY - Only the brave ventured onto the streets of Sydney yesterday, and then only for the briefest possible trips.

Pedestrians hurried along, collars turned up, coughing and choking as red dust blown in from the Outback swirled around them, lodging in their eyes, nose and throat.

Many people wore face masks, making the usually laid-back city look like Hong Kong during the recent swine flu scare.

Motorists kept windows firmly shut, and those who could stayed indoors, as strong winds continued to whip up the dust, along with rubbish and street debris.

Earlier, Sydneysiders woke up to orange skies, with the dawn sunshine struggling to penetrate a dust cloud suspended over a city blanketed in red.

The cloud cast an eerie glow, which some locals mistook for approaching bushfires. Emergency services and radio stations received hundreds of calls.

With Sydney enjoying a spring heatwave, many locals had left windows open overnight. In the morning, they found their floors covered in dust, which had also swept in beneath doors.

Washing hung on the line was bone dry from the warm winds, but coated in an unpleasant brown grit.

Commuters did their best to avoid breathing in the dust, swathing themselves in scarves or holding handkerchiefs to their faces as they fled inside train stations and on to buses, throats dry and eyes stinging.

Motorists stepped outside to find their cars - and everyone else's - plastered with thick dust. When they attempted to clean their windscreens, the dust became red-brown sludge.

Tourists rash enough to venture out discovered the Sydney Opera House had turned orange, while the Harbour Bridge was visible only in silhouette because of low visibility.

The blood-orange backdrop to the city skyline provided plenty of fodder for photographers, who roamed the streets, snapping the peculiar scenes.

Sydney's beaches were bathed in a red glow, although that did not deter some dawn bathers and surfers from plunging into the waves. A few joggers and cyclists were also out and about, ignoring health warnings and watering eyes. The air was pierced by fire alarms, which went off in buildings across the city, triggered by dust particles.

The streets were strewn with rubbish blown out of the gutters, and with fallen branches and leaves. Morning newspapers delivered to homes had fluttered away, their pages scattered across the pavements.

Cars that were once white and green had turned brown.