Deadly Dust - The Importance of a Clean Workplace

The consequences of a dusty apartment likely only extend to a couple sneezes or the silent disapproval of guests. But in an industrial setting, the worst-case scenario is much more serious. In fact, dust explosions are among the deadliest of all industrial disasters.

But the materials associated with dust fires are often not ignitable in their typical form (you wouldn't be afraid to put a match to an ear of corn or a sheet of aluminum). Grind these materials up into fine powders, however, and you're dealing with a very different animal.

This is a problem for many industries. Particles have much more exposed surface in contact with the air than solid masses, resulting in a much faster and more violent explosion. Powders and dust can develop as a result of many different processes, including polishing, grinding, transporting, and shaping of different materials. Below is a list of different types of materials involved in dust explosions (Source: dustexplosion.info)

Three Significant Cases

Three of the most deadly dust explosions in the U.S. have occurred within the last decade.

The first of these happened on January 29, 2003 at the West Pharmaceutical Plant in Kingston, North Carolina. Half of the 150,000 square-foot plant was completely destroyed in a chain reaction of explosions that ripped through the plant, killing six people and injuring thirty-six others. The shockwave was said to have broken windows up to 1,000 feet away and propelled debris over two miles. The explosion was the result of a synthetic rubber processing machine, which dipped strips of rubber in finely powdered polyethylene. The ventilation systems were (unbeknownst to the workers) collecting this polyethylene dust on the top side of the ceiling. Investigators believe that the dust was ignited after being disturbed and subsequently suspended in the air.

The second explosion happened less than a month later at the CTA Acoustics manufacturing plant in Corbin, Kentucky. The facility produced fiberglass insulation for the automotive industry. The explosion was fueled by a phenolic binder resin dust which accumulated in the production area and was likely ignited by flames from a malfunctioning oven. The explosion killed seven workers and injured forty others.

A third explosion occurred a little over 4 years ago, February 7^th, 2008, at an Imperial Sugar factory in Port Wentworth, Georgia. The initial explosion occurred in the center of the old, four-story refinery, where the sugar was bagged by workers and stored. The explosion caused 13 deaths and 42 injuries. This video provides details surrounding the incident.

What Can Be Done?

Some 30,000 factories in the U.S. are vulnerable to dust explosions based on their operating environments and the substances they work with. Since 1980, around 350 of these explosions have occurred, resulting in 133 fatalities and many more injuries.

So what has gone wrong with these many disasters? I expect that most of these accidents (including the three cases above), can be linked to negligence or ignorance of the associated hazards.

[Nobody thought that sugar dust could do this… Source: CSB.gov]

One of the keys to preventing dust fires and explosions is an understanding of the importance of a clean workplace. News reports regarding the CTA Acoustics explosion revealed that inspectors weren't trained to recognize dust as a critical safety hazard. The same was true for most of the plant workers, who may have said something about the accumulation if they had known. Recognizing the need to keep the facilities clean and relatively dust free would have likely prevented the catastrophic explosions from occurring.

But like all problems, there are many other factors that could provide the ingredients for a dust fire (namely its fuel or ignition source). Hot surfaces, electrical devices, and friction points can all cause ignitions when exposed to sufficient concentrations of particles, and thus equipment needs to be properly designed and maintained (see image below for a chart of responsible ignition sources - Source: dustexplosion.info). Other factors, such as the introduction of open flames or foreign materials by workers, can be prevented by common sense.

Proposals for new safety legislation and standards are still pending 4 years after the Georgia sugar refinery explosion. The difficulty is that many employers do not follow current OSHA safety regulations as they stand.

"It's been on the books since the early 70s. If employers comply with the housekeeping standard, then they have eliminated dust, and you cannot have a combustible dust explosion," says Ed Foulke, the head of OSHA.

I'd like to think that the failure to comply is a failure to understand the possible consequences - a mindset that it is a nuisance to productivity coupled with the "it won't happen to me" syndrome. I can understand this attitude - I sometimes convince myself that a little "organized chaos" is the most productive management system for my own workspace. But then again, my workspace isn't likely to spontaneously combust if it gets too messy…

References:

CBSNews - Is Enough Done to Stop Explosive Dust

Interstates - Preventing Dust Explosions

NFPA Journal - Dust to Dust

OSHA - Combustible Dust In Industry