The BC Safety Authority says a fire last year at a Burns Lake, B.C., sawmill is not likely linked to the fatal fire that destroyed the mill earlier this month.

High concentrations of dust in the air were detected at the Burns Lake mill in November. (Jonathan Hayward/Canadian Press)

BCSA spokesperson Stephen Hinde says a February 2011 fire at Babine Forest Products was probably caused by an electrical malfunction, which caused an electrical switch to spark, igniting sawdust.

He declined to speculate on the cause of the fire at the mill earlier this month, which killed two people, injured 19 others and destroyed the town's main employer.

But Hinde said it's not likely to have been caused by a similar event.

"In my expert opinion, based on my experience, the nature and causes of the fire in 2011 were not likely to have caused an event like we have seen in 2012. In and of itself, the event in 2011 did not release enough energy to explain the magnitude of damage that we have seen in 2012," he said.

"At this point, we still have an ongoing investigation, we're not ruling out any possible cause, but the sudden and massive release of energy that we have seen in the 2012 event is highly unlikely to have been caused by an event similar to 2011."

'Small dust explosion'

A BCSA report filed after the 2011 incident indicates sawdust likely contributed to the fire.

"Examination of equipment in the vicinity of the switch identified sawdust accumulation in and on equipment," the report. "The sawdust appeared to be unusually dry due to the wood source [pine beetle-killed wood] and preceding weather conditions."

Investigators could not determine exactly how the fire started.

"[Whatever the ignition source], this ignited surrounding combustibles [wood dust]," the report says.

"If there was dust accumulation within the equipment, the small explosion ... may have stirred up enough dust to cause a small dust explosion ... thereby further propagating the fire."

No one was killed or injured in that fire. Damage was estimated at $500,000.

Several mill workers told CBC News after the fatal fire earlier this month about high levels of dust in the facility, which can be an explosion hazard.

A WorkSafeBC report written just weeks before the fire noted dust levels in the mill's basement were more than twice the acceptable level.