West Pharmaceuticals has agreed to a settlement with the North Carolina Department of Labor over 86 violations stemming from a devastating explosion in January at its Kinston, N.C., plant that killed six people.

Violations pertain to electrical systems, employee training and combustible dust that was trapped in the ceiling and exploded.

West will pay $100,000 in fines and pay $300,000 to local charities who helped on the day of the explosion.

The Labor Department originally issued $602,000 in fines. West negotiated that down to the $400,000. It is building a new plant in Kinston.

U.S. Chemical Safety Board investigators concluded that a dust explosion occurred above an area where rubber strips were coated with moistened polyethylene powder. Investigators said the five conditions necessary for a dust explosion were all met at the West plant: fuel, oxygen, dispersion, confinement, and ignition.

"I don't think anybody out there knew the dust was going to explode," one employee told local TV station WRAL News.

By installing a suspended or false ceiling years earlier, the company inadvertently created an area where dust could accumulate out of view, and also created a space where a dust explosion could occur and spread, according to the investigation. During the production process, the plant's ventilation system drew fine dust particles into the space above the unsealed, suspended ceiling, where the dust settled and built up.

Weeks prior to the explosion, maintenance workers had seen layers of dust coating surfaces above the suspended ceiling, according to the report.

"Tragically, there was no recognition of the explosion hazard posed by this accumulated dust," said one investigator.

"We never had any training. We were never told that the dust could explode," one employee said.

U.S. Chemical Safety Board Chairwoman Carolyn Merritt.said: “The dangers of explosive dust are not well known, and helping industry to understand this insidious hazard certainly will be a priority."