Combustible Dust Dangers: Too Dangerous for a 'Wait and See' Approach
"Combustible dusts," defined by their tendency to ignite when suspended in air, come from many sources, including sugar, flour, feed, plastics, wood, rubber, textiles, pesticides, pharmaceuticals, dyes, coal, and metals. Dust explosions can destroy buildings and hurl people across a room. People caught in dust explosions are often burned by the intense heat within the burning dust cloud or injured by flying objects or falling structures.
A quick review of combustible dust incidents underscores the seriousness of this issue:
The U.S. Chemical Safety and Hazard Investigation Board (CSB) identified 281 combustible dust incidents between 1980 and 2005, with 119 workers killed and 718 injured.
CSB reports 70 new incidents since 2006.
In 2003, three catastrophic dust explosions killed 14 workers.
In 2008, an explosion at a Georgia sugar refinery killed 14 and injured more than 40 in one of the deadliest industrial incidents in three decades.
At a Michigan electrical power generation facility, six people were killed and 14 injured when natural gas from a boiler exploded, setting off another explosion caused by disturbed coal dust.
At a rubber fabricating plant in Mississippi, five died from burns and six were seriously injured during an explosion involving accumulations of highly combustible rubber dust.
At a pharmaceutical plant in North Carolina, six died and dozens were injured in an explosion and fire fueled by plastic powder accumulating above a suspended ceiling/ In the aftermath, hundreds more lost their jobs.
At a Kentucky fiberglass insulation plant, seven employees were killed by an explosion and fire fueled by resin.
At a wheel manufacturing plant in Indiana, explosions of accumulated aluminum dust severely burned three employees, one fatally.
The list goes on, involving a wide range of industries and types of combustible dust. This is a list your organization never wants to be on, yet OSHA estimates 30,000 U.S. facilities may be at risk for combustible dust incidents. This article provides background on combustible dust issues to help you evaluate whether your organization is doing everything it can to minimize that risk.
Understanding the Problem
One of the best ways to prevent these explosions is to minimize dust accumulations. The good news is that you and your workers can have a huge impact in this area. Ensuring good housekeeping, designing and maintaining equipment to prevent dust leaks, using dust collectors, eliminating flat surfaces and areas where dust can accumulate, and sealing hard-to-clean areas (such as the area above a suspended ceiling) can effectively prevent or at least minimize the severity of flash fires and dust explosions. Conversely, contributing factors behind the combustible dust incidents described earlier include:
Workers and managers were unaware of dust explosion hazards or failed to recognize the serious nature of dust explosion hazards.
Facilities failed to conform to existing standards that would have prevented or reduced the effects of the explosions.
Procedures and training to eliminate or control combustible dust hazards were inadequate.
Warning events were accepted as normal, and their causes were not identified and resolved.
Dust collectors were inadequately designed or maintained.
Process changes were made without adequately reviewing them for the introduction of new potential hazards.
Housekeeping is critical. In a "60 Minutes" interview, former OSHA Assistant Secretary Edwin Foulke Jr. stated, "If the employers comply with the housekeeping standards, it would eliminate or at least mitigate the hazard of having a combustible dust explosion." Improper housekeeping, including forceful sweeping and cleaning with high-pressure compressed air or steam, can create dust clouds--a fire and explosion hazard. Proper housekeeping requires know-how and sometimes additional effort.
Training is critical, including a relevant, compelling message that explains the reasons for precautions as much as the precautions themselves. Simple awareness is not enough. People must know about external incidents and gain a realistic perception of the risks involved.
The Regulatory Situation
In the absence of a comprehensive standard on “combustible dust” for general industry, the CSB, American Society of Safety Engineers, interest groups, and some in Congress have urged that new OSHA standards be created. And regulatory change may be on the horizon. U.S. House Bill 5522, The Combustible Dust Explosion and Fire Prevention Act of 2008, asked that OSHA implement a federal standard based on National Fire Protection Association (NFPA) consensus standards. The House passed the bill in 2008, but it stalled in the Senate with President Bush threatening a veto. The bill has been reintroduced and is likely to have more support from the new administration.
Proponents also point out that OSHA did implement a combustible dust standard for grain handling facilities in 1987 and a 2003 report found it had been quite effective, reducing grain dust explosions by 42 percent and injuries and fatalities by 60 percent, and preventing an estimated five deaths per year.
Recommendation: Act Now
Given the uncertainty about regulatory changes, some organizations have adopted a "wait and see" approach with regard to combustible dust. However, the absence of a comprehensive standard should not influence safety decisions, nor should you overlook federal and industry consensus standards that do exist, such as NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids.
Even in the absence of a comprehensive standard:
1. OSHA can cite facilities right now using standards defined by its Combustible Dust National Emphasis Program (NEP), CPL 03-00-2008, including electrical installations, housekeeping, hazard labeling, PPE hazard assessment, and the employer's duty to provide a workplace free from recognized hazards. In March 2009, $65,000 in penalties were levied against a sugar manufacturing facility based solely on the NEP.
2. Companies may be held civilly liable right now based on consensus standards.
3. Increasingly stringent state, local, and organization-specific requirements are being adopted and policed right now by insurance risk managers, OSHA state agencies, and fire marshals.
4. Awareness of this issue is high among employees and community stakeholders because of media attention, including a "60 Minutes" piece titled "Is Enough Done to Stop Explosive Dust?" If your organization isn't addressing this issue, you run the real risk of someone's filing an OSHA complaint.
The wisdom of acting now with regard to combustible dust doesn't change the fact that improvements to dust collection systems, electrical equipment, wiring, and other facility upgrades typically require significant human and financial resources--a tough sell when budgets are tight and cost-reduction efforts are critical. Objective data are needed to make effective--and cost-effective--control recommendations. An important first step is a hazard and risk analysis to determine needs and prioritize implementation. If controls cannot be implemented now, plan and commit resources for future implementation, then seek interim control measures.
Facilities should carefully assess the following:
- Materials that can be combustible when finely divided
- Processes that use, consume, or produce combustible dusts
- Open areas where combustible dusts may build up
- Hidden areas where combustible dusts may accumulate
- Means by which dust may be dispersed in the air
- Potential ignition sources
Of course, the effectiveness of any control will depend wholly or in part on people. Your people should be trained to recognize and prevent hazards associated with combustible dust, as well as understand the overall plant programs for dust control and ignition source control. Periodic retraining should refresh knowledge and cover hazard or process changes. It is crucial that such training drive home the value of controls, educating your workforce about the risks, hazards, and precautions within their control, particularly if extra effort is required. Without employee buy-in, least-effort methods of dust relocation such as compressed air may find favor over safer vacuum cleaning methods. Don't run the risk of wasting capital on processes and equipment that aren't used as intended.
Combustible dust incidents can be devastating. These incidents will continue if action is not taken. Don't wait; evaluate your operations, check OSHA and NFPA standards, implement effective controls, and train your workforce to take this threat seriously and know how to avert it.
1. OSHA Combustible Dust National Emphasis Program
2. US Chemical Safety & Hazard Investigation Board – Combustible Dust Hazard Study