According to employees at the scene, the dust that had caught fire was starch, which is one of the examples of a combustible dust OSHA uses. The cause of the fire is not yet known and is under investigation.
The burning dust created a large fire that produced thick black smoke and flames that were able to burn through the roof. A member of the Chattanooga Fire Department explained how severe it was: “There was a pretty decent fire inside, and any time flames break through the roof it’s a big deal“.
Luckily the dust was contained within the collection system and the fire didn’t create a dust cloud. If the fire had disturbed surrounding dust it could have created a cloud and caused an explosion. Combustible dust explosions occur when explosive dust particles become suspended in the air to create a cloud, and this cloud comes in contact with an ignition source. Past combustible dust explosions have had enough explosive power to lift the roof off a building or buckle cement floors, and usually cause large amounts of damage and injuries.
Since it was a contained fire and not an explosive dust cloud there were no reported injuries and the dust fire was brought under control before it caused extensive damage. However, this plant has had serious issues with worker safety in the past.
In February 2015 a Wrigley Plant worker was killed when he was crushed by a piece of machinery, and in October 2013 a worker died during an industrial accident at the plant, which OSHA found Wrigley responsible for.
Employees worried about jobsite safety can anonymously ask questions, file a complaint, or report hazards by calling OSHA’s toll-free hotline at 800-321-OSHA (6742) or https://www.osha.gov/as/opa/worker/complain.html