Smoke from a tip fire the size of a sports field has forced the evacuation of more than 100 homes in Melbourne, with four people taken to hospital.
Firefighters have doorknocked 115 homes in Dallas telling residents to get out and more evacuations could be necessary as the fire at SKM Recycling in Coolaroo continues to burns 24 hours after it started.
"It is the size of a sports field, it is as high as a factory," Emergency Services Minister James Merlino told reporters on Friday.
"It is highly likely that there will be further recommendations to evacuate."
The MFB expects it will take three days to get control of the fire which started in a heap of cardboard, paper and plastic on Thursday morning.
The Environment Protection Authority has declared air quality across the affected areas to be of "very poor" quality.
"If you choose to stay, emergency services may not be able to help you," the evacuation warning says.
Ambulance Victoria treated eight patients suffering from smoke-induced asthma symptoms, while four others, including a four-year-old girl, were taken to hospital for smoke-related respiration problems.
EPA chief executive Nial Finegan said there was going to be a planned inspection at the centre on Thursday, before the fire took hold.
"That shows concern on the site," he told reporters.
The site previously caught fire in February, June and again on Wednesday night, in an unrelated blaze.
Opposition Liberal emergency services spokesman Brad Battin said no one was taking responsibility for the fire.
"No one wants to take responsibility... the government must step in [and] explain to the people why they aren't in their homes today," he told ABC radio.
A watch and act warning for smoke remains in place for a number of suburbs across Melbourne's north including Broadmeadows, Campbellfield, Fawkner, Glenroy, Jacana, Westmeadows.
Residents in neighbouring suburbs are being told turn off air-conditioning and heating and close windows and doors.