OSHA’s New Combustible Dust Standard: A Look Into the Future


You may have read in one of our recent blog posts that OSHA has announced its upcoming regulatory agenda.At the top of the list is the creation of a new Combustible Dust Standard. That’s literally true–it’s the first item on OSHA’s list. But it’s probably also metaphorically true for a lot of you–the creation of a brand new standard with potentially far-reaching effects is going to interest a lot of you.


So, we thought we’d give you the the skinny on OSHA and combustible dusts, providing some background, some places to look for information, and some hints about what OSHA may be up to.

Buckle your seat belt, we’ve got a lot of ground to cover. (We probably should have followed the naming convention of our earlier post on the 2012 HazCom alignment with GHS and titled this post “Everything You Always Wanted to Know About Combustible Dusts But Were Afraid to Ask.”)


WHAT IS COMBUSTIBLE DUST?Here’s how OSHA defines it in their current National Emphasis Program on Combustible Dust:

A combustible particulate solid that presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations, regardless of particle size or shape.

HOW CAN DUST COMBUST AND CREATE AN EXPLOSION?Before a dust explosion can occur, five elements must be present:

  • Fuel (the dust)
  • Oxygen from the surrounding air or other sources
  • An ignition source, such as static electricity, electric arc, a glowing ember, a hot surface, welding slag, frictional heat, or flame
  • Dispersion of the combustible dust particles into a dust cloud suspended in the air
  • Confinement of the dust cloud, such as in a vessel, room, building, enclosure, or ductwork

Those five elements make up what is called the Dust Fire and Explosion Pentagon (see image below). If all five are present, dust can combust and create an explosion. If any one of the five are absent, there will be no explosion.


WHY IS A COMBUSTIBLE DUST STANDARD NECESSARY?In short, because a lot of people die or get injured as a result of combustible dust explosions. And the property damage is immense and costly, too.

According to a study by the Chemical Safety Board, 281 combustible dust incidents between 1980 and 2005 killed 119 workers and injured another 718. That’s a lot. And that doesn’t count more recent incidents–such as a 2010 titanium dust explosion that killed three workers or the 2008 Imperial Sugar combustible dust explosion that killed 14 and injured 36.

WHAT CURRENT REGULATIONS ADDRESS ASPECTS OF COMBUSTIBLE DUSTS?OSHA has never had a standard specifically about combustible dust. But they do have existing regulations that address aspects of combustible dust hazards. Those regulations are:

WHAT GUIDANCE HAS OSHA CREATED ABOUT COMBUSTIBLE DUSTS SO FAR?Although OSHA has no specific Combustible Dust Standard yet, they have created fact sheets, bulletins, posters, publications, and webpages addressing the issue.

Here’s what they’ve done so far:

WHAT ABOUT OSHA’S COMBUSTIBLE DUST NATIONAL EMPHASIS PROGRAM?Yep, you’re right. OSHA didn’t stop at just creating some posters and fact sheets.

They also created a Combustible Dust National Emphasis Program in 2008 and published a Status Report on the Combustible Dust National Emphasis Program in October of 2009.

SO WHAT HAS OSHA DONE SO FAR IN TERMS OF CREATING THIS NEW COMBUSTIBLE DUST STANDARD?There’s been quite a bit going on. Here’s a handy-dandy list if you want to research it further:

  • Advanced Notice of Proposed Rulemaking (ANPRM)
  • Stakeholder meeting, Washington, DC, December 14, 2009 (summary notes)
  • Stakeholder meeting, Atlanta, GA, February 17, 2010 (summary notes)
  • Stakeholder meeting, Chicago, IL, April 21, 2010 (summary notes)
  • Expert Forum, May 31, 2011 (summary notes or get it in a PDF)

COULD SOMEONE AT CONVERGENCE TRAINING READ ALL THAT AND SUMMARIZE IT SO I DON’T HAVE TO?Sure. How about if we summarize that Expert Forum, since it’s the most recent thing that happened?

They focused on four main topics. Those were:

So let’s break down those four main topics and give you an idea of what they talked about in each.


There are a few interesting things in the introduction to this section, notably:

  • “The broad scope has caused OSHA to contemplate different rulemaking approaches, such as a performance-based approach versus a specification approach that mandates use of certain engineering and administrative controls.”
  • “…the challenge OSHA faces when developing the combustible dust standard is writing an effective rule that covers a wide variety of processes, but at a reasonable cost.”
  • “OSHA recognizes that including all facilities with any amount of combustible dust on site, regardless of the magnitude of the actual hazard, is inappropriate. However, the balance OSHA has to achieve with respect to scope is to avoid costs for employers with facilities where the hazard is minimal while assuring that facilities with serious combustible dust hazards are brought into the scope of the standard.”In the context of that introduction, here are the various big issues the experts weighed in on:
    • “Would it be appropriate to exclude certain materials based on their explosibility? Should the exclusion go beyond noncombustible dusts to some minimally combustible dusts as well? If so, what criteria would appropriate? There are dusts in the low Kst range that have produced fatal incidents – including, most strikingly, sugar dust.”
    • “Would it be appropriate to exclude industries that have a history of fewer incidents? Fewer incidents with injuries? Fewer incidents with fatalities? Where should the cutoff be?”
    • “Would it be appropriate to exclude smaller entities? If so, should this be based on facility size, number of employees, or some other threshold? If not, would a different level of controls be appropriate?”
    • “Are there any other scope-limiting approaches that would be appropriate?”

    And other topics discussed more briefly included:

    • The role of risk in defining the scope
    • The difficulty of anticipating all hazards in the standard (an example was given of an explosion caused when combustible dust was pneumatically conveyed through nonconductive piping, which caused an electrostatic discharge that triggered an explosion)
    • The possibility of adding materials that are thermal decomposition hazards (such as benzoyl peroxide) instead of merely combustible dust hazards to the incident list provided by OSHA (the expert was opposed to this idea)

    Focus on Preventing Secondary Explosions

    During this part of the meeting, the experts discussed the idea of having a Combustible Dust Standard that focused on preventing secondary events. The reason for considering this is that the most catastrophic events tend to be secondary explosions.

    It was noted that there were two ways to accomplish that goal:

    • Omitting “all requirements that only prevent primary explosions,” such as ignition controls
  • Omitting “requirements that only mitigate the effect of explosions after they are initiated,” such as explosion ventingIn the context of that introduction, here are the various big issues the experts weighed in on:
    • “Would focusing on secondary explosions prevent most multi-fatality events? How could OSHA estimate the number of incidents or fatalities prevented by such an approach? Is data available that indicate whether fatalities were due to primary vs. secondary events?”
    • “What would be the impact of omitting provisions that only address primary explosions? An example would be ignition-source controls within processing or dust-collection equipment.”
    • “What would be the impact of omitting provisions that minimize the effects of an incident, were one to occur? Examples include explosion vents and explosion-suppression systems.”
    • “Is there a simple way to define quantities of dust that are necessary to trigger cleaning action to prevent secondary explosions? Specifically, what method could be implemented by small entities without calculations or outside expertise?”
    • “How much dust accumulation on horizontal surfaces results from failure to install or maintain dust-collection systems as recommended in the NFPA standards? For example, if NFPA-recommended dust-collection equipment was to be omitted from a packaging operation, the fugitive dusts emitted, but not captured, would eventually accumulate on surfaces.”

    Along with those big issues, several of the experts made suggestions and provided examples that “the cost of mitigating primary deflagration hazards can be relatively small compared to the cost of managing fugitive dust.”

    Existing Facilities

    This part of the meeting focused on whether all parts of the new standard should apply to existing facilities. In that context, the introduction included the following points of interest:

    • “…some requirements of the grain handling facilities standard did not apply to existing facilities. Accordingly, he asked the experts: Should the combustible dust standard adopt a “grandfathering approach,”; or are some engineering controls important enough to warrant installing at existing facilities? As one example, OSHA must consider whether existing facilities should be required to retrofit their dust collection systems to be consistent with current consensus standards that were not available at the time the original facilities were constructed.”
  • “Mr. Chibbaro (OSHA) added that a typical hierarchy of safety controls places engineering controls above administrative controls. However, in an explosion scenario, the hierarchy is modified so that controls that prevent an incident from occurring (engineering or administrative) are ranked above those that mitigate the consequences of an incident.”Given that focus, here are the big issues the experts discussed:
    • “OSHA is concerned about the burden on employers if existing facilities must retroactively comply with the standard, especially the higher-cost engineering controls. Are there situations where engineering controls are not essential for existing facilities and, if so, how could they be defined in a standard?”
    • “Data available to OSHA indicates widespread non-compliance with engineering control provisions of NFPA standards. Has compliance improved in the last few years as a result of increased hazard awareness and government enforcement efforts? If engineering controls were not mandated, how likely are they to be installed voluntarily, and in what situations?”

    Multiple Layers of Protection

    In this fourth–and last (whew!)–big topic, the experts discussed the use of multiple layers of protection to address combustible dust hazards.

    During the introduction, an OSHA representative used the analogy of the multiple safety measures intended to protect people in cars: Drivers are tested and licensed, but we also have seat belts, antilock brakes, air bags, and traffic signals. The OSHA representative then “asked the experts to consider the extent to which multiple layers of protection might be necessary in OSHA’s combustible dust standard, keeping in mind the concerns of small business, cost effectiveness, and employee protection.”

    So, with that introduction, the experts went on to discuss these big issues:

    • “Would it be appropriate for OSHA to require a single layer of protection against dust explosions – for example, housekeeping without ignition controls or explosion mitigation features?”
  • “OSHA’s current standards include controls for certain ignition sources, including electrical equipment, powered industrial trucks, and welding. Would it be necessary for employee protection to require controls, in addition to housekeeping, for ignition sources such as static electricity, friction, sparks, hot surfaces, open flames, or smoking?”
  • “If engineering controls were not mandated, what layers of protection would be appropriate?”
  • “In your expert opinion, what should be the hierarchy for protection for combustible dust hazards (dust control, ignition control, explosion mitigation)?With that, the meeting was concluded. During the conclusion, it was mentioned that the next step in the process was the upcoming Small Business Regulatory Enforcement Fairness Act (SBREFA) panel, which the Unified Agenda says will happen in October, 2013.


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