More than 80 percent of combustible dust incidents are fires, most of which cause minor property damage.

Better Identification of Fire Hazards Needed

Stakeholders seeking control measures to minimize the probability and severity of combustible dust incidents should work more closely with the fire service.

Combustible dust-related fires occur with alarming regularity throughout the manufacturing, non-manufacturing, and utility sectors. In 2008 following the tragic Imperial Sugar Refinery dust explosion, the Combustible Dust Policy Institute discovered through researching media accounts that more than 80 percent of combustible dust incidents were fires. The majority of these fire incidents sustained minor property damage with no fatalities and minimal injuries.

Normalization of Deviation
A troubling situation arises when nothing catastrophic follows recurring combustible dust-related fires. Illuminating histories of catastrophic dust explosions investigated by the U.S. Chemical Safety Board (CSB) during the past eight years indicated that, prior to deadly dust explosions, facilities experienced numerous non-threatening combustible dust-related fires.

Fire service professionals, facility owners, occupational safety managers, and workers misinterpret that the manufacturing process is safe following a minor combustible dust-related fire, especially when, in most instances, the small fire is suppressed by the workforce with fire extinguishers and a fire department response is not required.

This is a false interpretation that all is okay following these non-consequential fires. The notion that through random luck a catastrophic dust explosion hasn't happened yet further reinforces this false interpretation. This train of thought is referred to as "normalization of deviation," such as in the repeatable combustible dust-related fires that seem a normal part of the process.

National Fire Incident Reporting System
On a much larger scale, the problem is not being thoroughly recognized at the national, state, and local fire service organizational levels. In contrast, fire department personnel are the first to respond to combustible dust-related fires. When fire department personnel return to the local fire station following response to fires, they voluntarily report the incidents either manually or electronically to the State Incident Reporting Authority, which many cases is the state fire marshal, utilizing the automated National Fire Incident Reporting System (NFIRS 5.0). The State Reporting Authority then forwards the incident data to the National Fire Data Center administered by USFA, the U.S. Fire Administration.

A problem arises in this national reporting system where there are no data elements specifically identifying manufacturing process equipment involved in ignition of combustible dust. If process condition fire hazards can't be identified, then how can they be controlled through administrative and best engineering practices?

An endless, frustrating cycle continues and, as time goes by, the fire department returns to suppress yet another repeatable, dust-related fire where there are no injuries and minimal or no property damage in most instances. Now, there is normalization of deviation among all stakeholders concerning the lack of comprehensive combustible dust fire prevention and control measures. But let's not forget that all big fires or catastrophic dust explosions started out as small fires.

Confined Structure Fires
Many combustible dust incidents are similar to confined structure fires such as in a flue, commercial compactor, incinerator overload/malfunction, contained trash, cooking, and fuel burner/boiler fires. Confined structure fires are fires in non-combustible containers that rarely result in serious injury and have no property losses due to flame damage, which is illustrated in the loss/1,000 confined fires according to NFIRS 5.0 data.

In 2009, NFPA Fire Analysis and Research compiled data from the NFIRS 5.0 database in addition to NFPA fire surveys and reported in "Structure Fires in Industrial and Manufacturing Properties" that 23 percent of equipment involved in ignition (EII) were confined structure fires. Prior to enhanced reporting measures of NFIRS 5.0, many confined structure fires were considered smoke scares by the fire service and not reported or were underreported.

Manufacturing process equipment such as pneumatic ductwork and dust collectors also are non-combustible containers. The NFIRS 5.0 system of USFA does not include many types of manufacturing equipment involved in ignition (EII) of combustible dust-related fires. One has to wonder whether incidents such as in the above process equipment are also considered smoke scares by local fire departments.

Equipment Involved In Ignition
The helpful NPFA report on fires at manufacturing facilities also identified that 23 percent, or $107 million, of direct property damage occurred at industrial and manufacturing facilities where the equipment involved in ignition (EII) was unclassified. This fact reaffirms that if equipment involved in ignition isn't identified (unclassified) in incident reports, then corrective control measures cannot be appropriately implemented.

Manufacturing fires are under the heading of nonresidential fires, which also includes storage in structures, public assembly, stores, offices, educational, and institutional facilities. USFA NFIRS structure fire data for 2003-2006 indicated manufacturing fires accounted for:

  • 1.4 percent of structure fires
  • 0.2 percent of structure fatalities
  • 1.7 percent of structure fire injuries
  • 4.2 percent of direct property loss of structures

While it is good news that the fatality and injury count is minimal following manufacturing fires, it should not deviate from continued proactive fire prevention and control measures so as to prevent future catastrophic events.

Reinforcing the idea that combustible dust-related fires are a subset of all fires and not a separate entity that has entirely different heat sources than the ignition of flammable gases, liquids, and vapors is absolutely essential. Most importantly, the only difference between these flammable products and combustible dust is vast differences in ignition sensitivity, such as minimum ignition energy (MIE) and flashpoint/minimum ignition temperature.

The CSB Dust Hazard Study
In 2006, the CSB released its "Combustible Dust Hazard Study" findings and proposed recommendations to OSHA, manufacturing sector stakeholders, and the public. This report was the direct result of the three catastrophic combustible dust explosions that occurred in 2003 in which CSB was the lead federal investigation team seeking root causes. The board noted in the report:

"… no federal or state agency keeps specific statistics on combustible dust incidents, nor does any single data source provide a comprehensive collection of all these incidents"

Readers of the study might be confused by the above statement, especially because the USFA National Fire Data Center collects specific statistics on all fires through NFIRS 5.0. This reporting system was initiated in 1976 when six states piloted an incident reporting system that is now referred to as NFIRS.

Process Fire Descriptors
NFIRS 5.0 reporting includes manufacturing fires that are classified as nonresidential structures. Combustible dust-related fires in manufacturing facilities would not be excluded from a NFIRS incident report. Quality of fire incident data is continually improved through input of state fire marshals via the National Fire Information Council (NFIC). A brief review of the "NFIRS 5.0 Complete Reference Guide" Fire Module provides excellent fire descriptors concerning heat source and factors contributing to ignition in regard to all fires, including combustible dust-related fires.

The numerous fire descriptors from the Fire Module are divided into three main sections. This offers insight into identifying combustible dust ignition hazards concerning process materials, process conditions (equipment), and process situations (ignition factors).

The NFPA 901 Standard
NFPA has done a superb job for many decades with dedicated technical committees diligently drafting combustible dust industry standards that provide workplace protection with fire/explosion mitigation and prevention measures. One standard of which many stakeholders might not be aware is NFPA 901 Standard Classifications for Incident Reporting and Fire Protection Data. This standard provides USFA, state fire marshals, and fire departments with numerous fire descriptor and data elements utilized in NFIRS.

The primary importance of NFPA 901 is that it assists in identifying fire/explosion hazards through incident-reporting methodology. The NFPA technical committee on incident reporting that incorporates fire data descriptors was formed in 1963, more than a decade prior to formal NFIRS reporting.

In contrast, the NFPA combustible dust standards are specific to control measures. A problem arises in identifying combustible dust hazards because NFPA 901 does not provide a specific data element on item first ignited of combustible particulate solids such as combustible dust. Instead, NFIRS utilizes the general fire descriptor data elements of dusts, fiber, lint, sawdust, and excelsior.

The problem is exacerbated when NFIRS 5.0 does not require entering the data element of type of item ignited when the above, item first ignited such as dust, is submitted in the NFIRS reporting form. Yet it is extremely important to identify the type of combustible dust, whether it is wood, chemical, plastic, paper, metal, food, etc., especially when all of these combustible dusts possess varying fire and explosion properties. How does one evaluate and control the hazard if identifying the type of combustible dust has been omitted?

A vision for the future is for all stakeholders who seek control measures to minimize the probability and reduce the severity of combustible dust incidents to work more closely with the fire service. Begin by inviting the local fire department to conduct a pre-fire inspection of your manufacturing process that notes the process material, conditions, and situations.

Initially, the combustible dust problem is a local fire prevention and control issue of maintaining life safety. It is secondarily an occupational safety issue. Good housekeeping will remove the fuel load for a catastrophic dust incident from secondary explosions. However, combustible dust-related fires and primary explosions will continue because of the inherent nature of the manufacturing process with materials, operating equipment, and ignition sources omnipresent.

Only the probability and severity can be continually minimized. A good start in the hazard analysis is identifying the hazard. NFIRS 5.0 provides an excellent resource in this area. It will take much needed input from all stakeholders for improvements in combustible dust-related fire incident reporting, and perhaps this article will provide a basic roadmap.

1. National Fire Incident Reporting System (NFIRS 5.0) Complete Reference Guide, US Fire Administration
2. Report on Confined Structure Fires-February 2006, US Fire Administration
3. U.S. Industrial and Manufacturing Property Structure Fires, October 2009, NFPA Fire Analysis and Research Division
4. US Chemical Safety Board, Combustible Dust Hazard Investigation, November 2006
5. NFPA 901 Standard Classifications for Incident Reporting and Fire Protection

This article originally appeared in the January 2011 issue of Occupational Health & Safety.

About the Author

John Astad is Director and Research Analyst of the Combustible Dust Policy Institute of Galveston, Texas. To contact him, visit

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