The men, aged 38 and 69, had been fishing in the Swan Bay area when they became disorientated and drifted offshore.

They called police around 1.30pm to say visibility was down to 100 metres and they didn't know where they were.

The pair was able to describe sea conditions near their boat and water police, using drift calucations, were able to locate them about 8km east of Jumpinpin Bar. The fishermen suffered dehydration and sea sickness but were otherwise uninjured.

The severe dust storm also kept fire officers busy.

Acting station officer at Cleveland, Craig Squires said two smoke alarms in commercial buildings in Victoria Point and Alexandra Hills had been activated by the dust.

"We responded to alarm activations and when we arrived there we had to isolate the smoke alarms as they were set off by the dust storm," he said.

Redland Hospital issued a health alert on Wednesday afternoon, warning people with respiratory conditions to be cautious about the dust haze.

Acting executive director of Population Health Queensland, Sophie Dwyer, said the main risk was dust irritation to the eyes, nose and throat.

"If dust is causing problems, people should keep windows and doors closed and if they have lung or heart conditions limit their exertion while the dust haze lasts," she said.

Victoria Point's Rod Murray said the dust was the thickest he had seen since 1987.

"The last time I saw one this thick was in Melbourne in 1987 when it was so thick, it prompted the street lights to turn on in the middle of the day," Rod said.