Sydney has been blanketed with high levels of thick dust, affecting visibility, brought on by gale force winds.
Major roads have been shut due to the high levels of dust, including the Sydney Harbour Tunnel and the M5 East Motorway from Beverly Hills to Kyeemagh.
Ferries have been suspended due to visibility and flights have been diverted from Sydney Airport. Police traffic co-ordinator, Senior Sergeant John Kane, said drivers need to be aware of the risks of driving through heavy dust.
"Drivers are continuing to drive at speeds which are high-risk in these conditions," he said.
"The dust has significantly reduced visibility on all roads and I am concerned that drivers are continuing to travel at speeds potentially dangerous in these conditions.
"All drivers should slow down until conditions improve."
Northwesterly winds from the western side of New South Wales have carried the dust to the city, according to the Bureau of Meteorology.
The dust is expected to dissipate later in the day.
Cars in the city are driving with their lights on this morning due to poor visibility.
Prolonged exposure to dust can result in asthma attacks, allergic reactions and other breathing-related problems, according to the NSW Department of Health.
People with respiratory conditions such as asthma, bronchitis and emphysema are urged to exercise caution.
Reports of raised dust are also coming in from Canberra, Newcastle and Tibooburra.