CSB calls for US combustible dust standard

30 July 2008

The US Chemical Safety Board has called on OSHA to act on a November 2006 CSB recommendation to adopt a comprehensive standard regulating combustible dust in the workplace. A serious explosion and fire earlier this year that killed 13 workers at Imperial Sugar's Georgia refinery and was caused when sugar dust was ignited and exploded, demonstrates the need for a new OSHA standard that would cover a range of industries exposed to this hazard.

Imperial Sugar's Georgia refinery

CSB chairman John Bresland told the subcommittee: “After witnessing the terrible human and physical toll from the Imperial explosion, I believe the urgency of a new combustible dust standard is greater than ever. A new standard, combined with enforcement and education, will save workers' lives.”

Bresland displayed photographs showing substantial amounts of sugar dust at the company's refinery in Georgia. These photographs were taken in 2006, Bresland stated, adding that testimony to the CSB indicates large amounts of sugar dust remained in the facility until the accident on February 7, 2008.

“Based on our evidence, Imperial did not have a written dust control program or a program for using safe dust removal methods. And the company lacked a formal training program to educate its workers about combustible dust hazards,” Bresland said. Imperial operators interviewed by the CSB had minimal knowledge of those hazards.

The CSB also recommended improved training of OSHA inspectors to recognise dust hazards, better communication of dust hazards to workers through material safety data sheets, and instituting a national emphasis program to better enforce existing standards - something which OSHA has now begun and for which. Bresland commended the agency.

“A comprehensive OSHA dust standard is necessary to get businesses, government inspectors, and insurers to identify dust hazards and take appropriate actions to control them. Existing standards do not clearly identify what kinds of dust are hazardous and only address limited aspects of how to control those hazards,” Bresland added.

“Instead of the present patchwork of miscellaneous federal, state, and local requirements, the CSB has recommended that OSHA develop a single, comprehensive, uniform standard – based on the sound, consensus-based technical principles and practices that are embodied in NFPA standards,” he claimed.

Multiple witnesses have told CSB investigators that there were large accumulations of sugar at many locations in the packaging plant. Near the powder mills, powdered sugar accumulated on the floor to a ‘mid-leg’ height. Airborne sugar in this room made it difficult for workers to see each other.

On elevated surfaces, witnesses described dust build ups of around an inch. National Fire Protection Association literature indicates accumulations of just 1/32 of an inch of dust covering just five percent of the available surface area, should be considered hazardous. An initial explosion in a plant can shake loose accumulations of dust elsewhere, suspending the particles that are then ignited, causing a powerful, secondary explosion.

Much of the electrical equipment in the plant was not dust-tight and therefore was not appropriate for use in plant areas where combustible dust could form an explosive atmosphere.

Bresland concluded: “I believe these findings are further evidence of the need for a comprehensive regulatory standard for dust. It is time for all the interested parties - industry, labour, and government – to move forward toward a standard that will protect workers, businesses, and communities well into the future.”