With no official answers on the cause of the Jan. 20, 2012 sawmill explosion and fire at expected for months, a number of theories about what could have caused such a large explosion and intense fire have surfaced.

Among them, the possibilities of a gas explosion or a combustible dust explosion.

A Dec. 28, 2011 WorkSafe BC report notes that pine wood dust levels in the sawmill's basement were in excess of the acceptable exposure level for employee's health sand safety. The report also said the current ventilation systems and water misters were not adequately protecting some workers.

Al Johnson, WorkSafe BC鈥檚 regional director said to media last week, that it is too early to speculate if the high dust concentration could be attributed to the catastrophic events at the sawmill. However, he did say that high dust levels can pose respiratory difficulties for mill employees and the risk of an explosion, but he noted that an ignition source would need to be present.

He said the investigation will take into consideration the reports about dust, a gas leak and any other instance that could have contributed to the disaster.

While investigating authorities have not yet attributed the blast to any sources, some Babine Forest Products mill employees have reported smelling gas, while others say that there was no smell of gas present at the time.

According to the U.S. Chemical Safety Board, combustible dust has caused a number of significant explosions and fires in processing facilities and mills, claiming multiple lives and leaving others with extensive burns.

Accumulated dust from a number of industrial sources including sawdust, rubber, coal, flour, pollen, grain, powdered milk, sugar, plastic and metals can ignite.

The say that as little as an ounce of dust can cause a serious explosion or flash fire.

亚洲天堂 reports have attributed combustible dust as the main source of fires and explosions in numerous processing facilities for over a century.

A gigantic explosion of flour dust destroyed the Washburn A. mill in Minnesota on May 2, 1878.

On Jan. 29, 2003, the West Pharmaceutical Services plant in Kinston, North Carolina was ripped apart by a violent explosion when a large rubber dust explosion obliterated the facility

In February 2008, an explosion rocked a Port Wentworth facility. After an investigation, the U.S. Chemical Safety Board concluded that the explosion was caused by ongoing releases of sugar dust from inadequately designed and maintained dust collection equipment, conveyors, and sugar handling equipment. Also, inadequate housekeeping practices allowed the highly combustible sugar dust and granulated sugar to build up throughout the refinery鈥檚 packing buildings.

During April 2010 a fiery explosion in a Kreamer U.S. Wood-Mode Inc. sawdust silo was the fourth in just seven years.

And powdered metal dust caused three explosions from January to May 2011 at the Hoeganaes Corporation in Gallatin, Tennessee.

On June 23, 2011, two Universal Woods sawmill workers were reportedly checking a filter for a dust collector with a metal rod around 3 p.m. when the rod touched something that caused a spark and ignited a dust explosion that rose more than 50 feet in the air.

The U.S. Chemical Safety Board say that combustible dust is a serious industrial hazard.

Many materials in a solid form may take large amounts of heat, flame, or energy to be combustible, but these same materials, reduced to a fine dust become highly combustible.

Over time, dust accumulation on surfaces like rafters, shelves and machinery can hold the potential to explode. Just one spark can result in a devastating chain reaction of events.

According to the U.S. Chemical Safety Board, as an explosion expands outwards, it produces a force that impacts the surrounding area. Accumulated dust can then be shaken off other surfaces to mix with the air and be ignited by the first explosion.

Even materials that are traditionally thought of as non flammable, such as metals, or slow burning, such as wood, can produce a powerful explosion when finely divided, and can be ignited by a small spark. A naked flame is not the only source of ignition for combustible dust.

Common sources of ignition include electrostatic discharge, friction, arching from machinery or other equipment and hot or over heated surfaces.

A common cause of electrostatic discharge is static electricity. Removing or preventing a buildup of static charge can be as simple as opening a window or using a humidifier to increase the moisture content of the air, making the atmosphere more conductive. Air ionizers  can perform the same task.

The U.S. Chemical Safety Board say that there are certain common elements necessary for a dust explosion and fire. The first of which is combustible dust, secondly an ignition source and oxygen and well as the dispersion of dust particles in sufficient quantity and concentration and the confinement of a dust cloud.

Bruce Clarke, Worksafe B.C. regional manager for the Prince George region and Scott McCloy, Worksafe B.C. director of communications said to Lakes District 亚洲天堂 last week that Worksafe B.C. has now taken over the investigation at Babine Forest Products and that they will be in town for as long as it takes to wrap up the investigation.

鈥淛ust because the public doesn鈥檛 see us, it doesn鈥檛 mean we are not still here,鈥� said McCloy.

He went on to say that they will be taking witness statements for quite some time and he urged anyone with any information, no matter how insignificant it may seem, to come forward. 鈥淲e will decide if the information is significant as the investigation progresses,鈥� he said.

They also urged locals, who think they may have a claim as a result of the incident at Babine Forest Products to come forward. 鈥淚t could be mill employees or first responders ... they may have questions they would like answers too, or may need help lodging a claim.鈥�

McCloy said that help is at hand, but added that all claims will  be reviewed before approval is given.

鈥淧eople should not be afraid to call, we have gracious and accommodating people on the phone lines waiting,鈥� Clarke said.

According to Clarke, the investigation will take months to unfold and he urged people to be patient.

鈥淭he sawmill site is large and highly dangerous. We need to be thorough. It is in the best interests of everyone that we are thorough.