"Pan Pac now has plans in place to rectify the cause of the incident as part of a wider programme of refurbishment and installation of back-up equipment planned for the kiln," Mr Ducker said.
The remedial work is not expected to be completed before mid-year, meaning full commissioning of the kiln will be as much as three years behind schedule, and general manager lumber Michael Raeburn said that includes agreement with workers on design, a 16-week manufacture period overseas and shipment.
"It is very much behind schedule."
He said that while the longer-term strategy is to have two more of the kilns the current priority is to ensure the kiln can be operated with the utmost consideration for health and safety of staff and the community.
Health and safety concerns relating to gas emissions emerged soon after the installation of the kiln at a cost of about $2.5 million early in 2014. Early last year four workers required medical treatment, and 85 workers went on strike.
Staff and contractors were provided with a written company reference for doctors if they had symptoms suspected of being related to breathing emissions, which said they could have been exposed to formaldehyde, acetaldehyde, formic acid, acetic acid, methanol and terpenes.
It was considered "highly unlikely" levels would have exceeded workplace standards, and tests last August showed levels of air pollutants were well below recommended guidelines when the kiln was operating normally.
But they suggested acrolein and acetic acid levels could exceed standards if a burner used to eliminate noxious gases stopped working during the kiln operation.
A WorkSafe spokesperson said yesterday the prohibition notice required Pan Pac to "engage with experts to establish a cause of the failure and undertake corrective action".
"They have done all of the above, they know what happened and they have taken corrective action to ensure the same problem does not reoccur," a statement said.
"In addition they have outlined to Worksafe their continued programme of development and self-imposed conditions that need to happen before they start commercial operation again."
WorkSafe is finalising its investigation into the kiln's malfunction and no decisions are understood to have been made on whether action will be taken.