Dust storms are again moving across parts of New South Wales from South Australia, as Sydney residents are warned they may face more storms later today.

Parts of western New South Wales are experiencing dust storms, which are expected to reach the coast early this morning.

Dust is moving through the Riverina in southern New South Wales.

BJ Wyse from Young says he can taste the dust in his house.

"Standing outside my place now looking at the clock tower, it's about half a kilometre away," he said.

"You can just see it with the thickness of it, you can just see the town lights it's just like a red glow.

"I just talked to a friend of mine in Cootamundra and it's going through there as well, so yep it's back again."

Massive clouds of dust are now blowing eastward through the state, where some regions are reporting visibility has dropped below 300 metres.

Barry Hanstrum from the Bureau of Meteorology says it is too early to predict exactly which areas will be affected, but he says it will not be as windy or as dusty as Wednesday.

"Wednesday morning's dust storm was an extraordinary event," he said.

"The winds we're seeing today aren't as strong as we saw on Tuesday and the area covered by these winds isn't as large.

"So while there's a reasonable likelihood of dust being in the Sydney area [on Saturday], it's unlikely to be as bad as what we saw on Wednesday."

Dr Wayne Smith from New South Wales Health says the department will issue health alerts if necessary.

"We're encouraging people to really check the weather reports on the radio and on the television," he said.

"Check the environment and climate change website for health warnings from particles. If they are clear on those then it should be safe for children to have outdoor activity."

On Wednesday, Sydney awoke to an eerie red dawn after strong north-westerly winds dumped thousands of tonnes of dust on the harbour city, the Hunter Valley, Wollongong and the state's west.

Hours later the dust cleared from Sydney and arrived in Brisbane, hampering firefighting efforts in southern Queensland by temporarily grounding water bombing helicopters.

The poor visibility hampered transport across the affected regions, slowed traffic and caused long delays at airports.

Emergency services received hundreds of phone calls from people with breathing difficulties.

For many, the clean-up continues.

Radioactive dust?

It is this type of weather event that award-winning documentary-maker David Bradbury claims could pose enormous health and environmental risks to a large proportion of the population, unless BHP Billiton contains radioactive dust from the planned expansion of its Olympic Dam mine.

"Given the dust storms of this week, which ABC TV news said originated from Woomera, which is right next door to Olympic dam Roxby, they could blow those tailings across the face of Australia," he said.

"The prevailing winds traditionally go east and, as we saw dramatically this week, [they] dump on our dense population centres.

"It will have much more major impacts than the James Hardie asbestos fallout that we've had over the last 40 or 50 years."

But a leading environmental toxicologist believes Bradbury's concerns are misplaced.

Associate Professor Barry Noller, from the University of Queensland's Centre of Mineland Rehabilitation, says that dust from metal and uranium mine sites is too large to be carried by the wind over long distances.

"In a big dust storm like we saw during the week, the dust is not going to come from one isolated site - it's going to be mixed in with dust from a whole huge area and diluted considerably," he said.

A spokesman for BHP Billiton says while the company is not prepared to debate the issue of dust, BHP Billiton does manage dust at its other Australian mine sites through extensive monitoring programs.