Officials are still seeking answers after more than 60 firefighters fought into the early hours of last Friday morning at Park Ridge to control a blaze furelled by old tyres in an abandoned warehouse.
Officials say they are determined to find out how it happened and who might have lit it.
Nearby residents were asked to shut windows and doors most of Friday, and those with breathing conditions were told to have medication handy.
Police and fire experts are investigating the forensics of the blaze.
And the Department of Environment and Science (DES) is asking questions of shed owners, around potential breaches of tyre stockpiling and the storage of chemicals.
DES officers said there were a large number of tyres and chemical drums at the site. There was also a need to prevent the release of contaminants in nearby waterways.
They would help firefighters determine the impact of the fire to the environment.
Firefighters were exhausted after a seven-hour battle with the flames.
“The operator does not have an Environmental Authority (EA) from DES to store tyres at this site,” a statement said.
“It is a criminal offence to stockpile tyres without an EA. The maximum penalty for stockpiling tyres illegally is $600,525 for an individual or $3,262,500 for a company.”
Police said the Koplick Road shed was alight at 11.30pm and created thick, toxic smoke.
Residents said houses were filthy in the aftermath of the fire.
A crime scene was declared on Friday.
Investigations are ongoing.
