Scientists have likened Victoria's coal mine fire to one of the deadliest environmental disasters in history.

The Hazelwood mine fire in the Latrobe Valley has been burning for nearly three weeks, sending thick clouds of coal smoke over Morwell.

While authorities have resisted calls for an evacuation, the elderly and children have been urged on Friday to leave the Morwell South community.

But experts are warning that severe air pollution from the coal mine fire should be taken far more seriously because it bears comparisons to a 1952 coal smoke disaster.

In that event, Londoners were blanketed in black coal smoke and smog for several days, killing an estimated 12,000 people.

Queensland University of Technology Professor Lidia Morawska, an expert on air pollution, said it isn't right to classify Morwell's smoke pollution as a short-term event and therefore as having little impact on health.

"The London fire duration is comparable to the Hazelwood fire," she said.

"There are many examples of health impacts due to much shorter exposure to combustion products than this fire."

Adrian Barnett, a QUT associate professor in health, said the dangers of coal smoke have been known for years due to epidemiological studies on the London smog.

"If I lived in the area I would move my family away until the fire was out," he said.

Morwell resident Estelle Landy said locals have been told to stay but can't.

"We can't sleep, we can't go outside, we can't breathe," she said.

Morwell resident Brian Marston says the poor air quality was affecting his asthma.

"Asthma wise, I'm on the puffer all the time and I'm inside all the time," he told AAP.

"When the smoke's around I've got to stay inside."

The Victorian coalmine fire has forced a judge to twice move a criminal trial 50km away from Morwell to Sale, while Australia Post has also confirmed it has temporarily suspended delivery rounds to Morwell street addresses.

"This decision has been made after careful consideration for the health and well being of our postal delivery officers, which is our primary concern," Australia Post said in a statement.

Several schools, kindergartens and childcare centres in Morwell have also been closed or relocated to the nearby towns of Moe, Traralgon and Yallourn North.