The hidden hazards of deadly dust
July 8, 2009
Since 1980, more than 130 workers have been killed by combustible dust explosions and nearly 800 others have been injured. As a result of these tragic losses of both life and property, a piece of legislation (H.R. 849) has been referred to the Subcommittee on Workforce Protection for the Congressional Committee of Education and Labor. It proposes significantly raising civil and criminal penalties for any combustible dust violations discovered by OSHA inspectors.
OSHA intensifies enforcement
OSHA has already begun to hire additional inspectors to support a new program to intensify the enforcement of existing combustible dust safety standards. In part, inspectors are charged with implementing OSHA’s Combustible Dust National Emphasis Program (CDNEP), which outlines a general requirement for employers to provide and ensure the use of protective equipment, including protective clothing, wherever an employee’s exposure to potential burn injuries from such explosions can be documented.
If employees are not wearing protective clothing such as flame-resistant (FR) apparel in areas of the plant where they may be exposed to potential combustible dust flash fire hazards, OSHA may issue citations under 1910.132(a) whether or not an accident precipitated an inspection.
For example, this past March, OSHA proposed more than $82,000 in penalties for a Georgia company after discovering latent combustible threats.
As part of its National Emphasis Program, OSHA has also been signaling its firm stance on protecting workers from combustible dust threats by citing NFPA 2113 â€” a standard that calls for wearing FR clothing wherever flash fires from combustible dust explosions could occur.
A bill similar to H.R. 849 died in committee last year, but the odds of successful passage this year have notably increased. Why? Because since the defeat of last year’s bill there have been combustible dust explosions in Georgia and Wisconsin. These have prompted Rep. George Miller (D-California), one of the bill’s sponsors, to state, “Our nation needs to act… (and) finally help workers and businesses stop these preventable and, all too often, deadly explosions.”
Prevention begins with recognition
The first step in a proactive PPE combustible dust program begins with recognition of a hazard. Although this sounds obvious, some facility managers could be unaware of combustible dust threats because they don’t associate their product line or processes with dangerous combustible byproducts.
The widespread nature of these threats has been researched by OSHA. The agency has identified more than 130 products or materials that pose a threat for combustible dust explosions. Industries that have combustible dust threats include food, tobacco, plastics, wood, rubber, textiles, pesticides, pharmaceuticals, coal, metals, and more.
According to the National Fire Protection Association (NFPA), combustible dust is generally a byproduct of “any industrial process that reduces a combustible material and some normally noncombustible materials to a finely divided state.” In adopting a proactive PPE stance, facility managers should take a “microscopic” look at their operations and identify all activities that have the potential to reduce materials into a finely divided state.
Eliminate ignition sources
Wherever potential dust hazards exist, always ensure that no ignition sources are present. Don’t think only in terms of open flames. Processes that create dust clouds, for example, can generate high levels of static electricity that need to be controlled through bonding and grounding of equipment. Rubber mats can be highly useful in preventing electrostatic sparks that contain more than enough energy to ignite combustible dusts or vapors.
Always be suspicious of simple “rules of thumb.” For example, a common misconception is that if anyone can see their thumb at the end of their extended arm, the environment is safe from combustible dust explosions because accumulation levels are not high enough to be dangerous.
In fact, the amount of accumulative dust required to cause an explosion can vary greatly based on particle size, air currents, room volume, physical barriers, and more. Every individual work area must be analyzed to determine its own unique profile in order to truly assess potential threats.
Always be mindful of areas where accumulation of dust can be hidden from view. Some of the greatest destruction caused by combustible dust explosions and fires in recent years have occurred as the result of initial explosions that led to secondary explosions of unseen accumulations of dust.
Following such individual area analyses, NFPA 654 can be a valuable reference guide. This standard (officially known as “Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids”) contains comprehensive guidance on the control of dusts to prevent explosions. Some of the standard’s recommendations include:
- Minimize the escape of dust from process equipment or ventilation systems.
- Use dust collection systems and filters.
- Utilize surfaces that minimize dust accumulation and facilitate cleaning.
- Provide access to all hidden areas to permit inspection.
- Inspect for dust residues in open and hidden areas at regular intervals.
- Clean dust residues at regular intervals.
- Use cleaning methods that do not generate dust clouds (if ignition sources are present).
- Only use vacuum cleaners approved for dust collection.
- Locate relief valves away from dust hazard areas.
- Develop and implement a hazardous dust inspection, testing, housekeeping and control program (preferably in writing with established frequency and methods).
Provide training and written instructions
A truly proactive PPE program also calls for regular employee training and outside contractor participation. Employees should undergo combustible dust training on at least an annual basis, and contract workers should be informed of potential combustible dust hazards related to their work and processes so they don’t inadvertently compromise the safety environment. And, naturally, ensure that all employees â€” as a final line of defense â€” are outfitted in flameresistant apparel.
Finally, put all your procedures and policies in writing for everyday reference. Prominently post “warning” reminders in all work areas so that everyone remains a proactive PPE proponent for ending any and all combustible dust threats.