Long before deadly mill explosions in Burns Lake and Prince George, the industry thought long and hard about sawdust.

It can be health hazard to breathe; it leads to deterioration of equipment; it has economic value.

And it can explode, killing people and destroying entire mills.

One way to control it is to create a space where powerful suction systems can pull it from the air and safely remove it to a baghouse capture system outside the mill.

Another is to open up ventilation so that dust — which may ignite and explode given a certain quantity in the air in the presence of a spark — isn't contained in a closed space.

But you can't push and pull at the same time — enclose and ventilate.

B.C.'s sawmilling industry is wrestling with questions about how to avoid a repeat of the Northern disaster that have killed four this year.

"Less dust is best is always your approach," said Bruce Luxmoore, mill manager at Interfor's Adams Lake Lumber. "It's deadly. It's difficult to maintain equipment in dust and people don't want to work in dust."

An industry panel announced Wednesday it has struck a task force to investigate combustion risks in mills.

A cause has not been determined in either mill explosion. Speculation, however, points to dust-related explosions caused by extremely dry dust from mountain pine beetle timber.

In addition to moisture content, risk from dust is related to its make-up — dirt versus wood — and particle size.

"This is probably the most trying time in our careers," said Ian Fillinger, general manager of International Forest Products (Interfor).

Deaths in B.C.'s lumber industry have occurred both in the forest and in mills, and not only through explosions. This week, a Kamloops millwright, George Park Jr., was killed at a Vanderhoof mill when a gate fell on him.

Two Adams Lake workers were killed in unrelated industrial accidents in 2007.

Since then, Interfor built a $100-million sawmill at Adams Lake to replace the six-decade old manufacturing facility. It remains B.C.'s newest.

In addition, the mill gets only about 30 per cent of its logs from mountain pine beetle timber. It also uses the lake as storage, which further cuts down explosion risk because moisture content is higher.

Many Cariboo and northern mills get 100 per cent of their supply from dead beetle wood.

Despite its lower risk and newest engineering, Adams Lake has undertaken new audits for dust control, is looking at engineered solutions to contain it and putting more people on the ends of brooms to clean it up.

Luxmoore noted, however, risk does not stem from dust sitting on a railing; it's dust in the air. How does the dust become airborne? Through vibrations, air currents?

Adams Lake will also install wall fans to increase ventilation where its investigation finds a need. Before the accidents it started a capital project to inject water mist into some areas.

Mill safety manager David Murray is a member of a WorkSafeBC working group studying dust in mills. He is researching two dust monitoring devices — one that captures it for lab analysis and another handheld realtime instrument.

"These devices have never been in the hands of our industry before," Fillinger said.

The answers on containing dust are complex and its link to explosions remain speculative. Both natural gas and propane remain possible fuel sources.

In addition to the engineered and manpower changes to increase vigilance on dust, Interfor officials said a major change in wake of the accidents is sharing information among companies — information traditionally jealously guarded due to potential competitive advantage.

Adams Lake Lumber was closed this week for a capital upgrade. On Monday, 150 workers will be back on the job.

"Guys are asking questions and we don't have all the answers at this point," Luxmoore said.