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Journal of Loss Prevention in the Process Industries 20 (2007) 523–529

www.elsevier.com/locate/jlp

Dust explosion incidents and regulations in the United States

Angela S. Blair�

U.S. Chemical Safety and Hazard Investigation Board, Washington, DC 20037, USA

Received 11 December 2006; received in revised form 1 March 2007; accepted 1 March 2007

Abstract

The U.S. Chemical Safety and Hazard Investigation Board (CSB) investigated three fatal dust explosions that all occurred in 2003.

These explosions caused the deaths of 14 people and injured hundreds more. Two of the facilities were damaged beyond repair, and

several hundred employees lost their jobs.

CSB’s investigations revealed that the explosions had common causes, despite their geographic and industrial diversity. Consequently,

CSB commissioned a study of combustible dust fire and explosion hazards. This paper presents a summary of CSB’s findings and

recommendations developed during that study.

r 2007 Published by Elsevier Ltd.

Keywords: Dust explosions; Chemical safety board; Hazard communication; Combustible dust; CSB

1. Introduction

The U.S. Chemical Safety and Hazard InvestigationBoard (CSB) investigated three fatal dust explosions thatall occurred in 2003. Several causal factors common to allthree of these dust explosions led CSB to commission astudy of combustible dust incidents and pertinent regula-tions, which were beyond the scope of the individualinvestigations. The study scope included analyzing theeffectiveness of government and private sector safetyprograms for dust explosion prevention.1

Major study findings are:

�

Nearly 300 incidents over a 25-year period caused over100 fatalities and 700 injuries. � Many material safety data sheets (MSDSs) for combus-

tible powders do not contain dust explosion hazardinformation.

� US safety regulations do not comprehensively address

dust fire and explosion prevention and mitigation.

e front matter r 2007 Published by Elsevier Ltd.

.2007.03.012

261 3607; fax: +1 202 974 7603.

ess: angela.blair@csb.gov.

�

Consensus standards provide guidance, but are volun-tary unless adopted by state or local jurisdictions as firecodes.

2. CSB combustible dust hazard study

2.1. History

CSB investigated three dust explosion incidents in 2003.On January 29, 2003, a massive dust explosion at WestPharmaceutical Services (West) in Kinston, NC, caused sixdeaths, 38 injuries, and virtually destroyed the facility(CSB, 2004). A second disastrous dust explosion occurredat CTA Acoustics (CTA) in Corbin, KY on February 20,2003. That explosion claimed the lives of seven workersand injured 37 others (CSB, 2005, CTA). Aluminum dustexploded at Hayes Lemmerz International (Hayes) inHuntington, IN on October 29, 2003, killing one workerand injuring six (CSB, 2005, Hayes) (Fig. 1).Deducing that broader common factors beyond the

scope of the individual investigations were likely involvedin these cases, CSB initiated a general combustible dusthazard study.

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Fig. 1. Aftermaths of the West (left), CTA (center), and Hayes (right) explosions in 2003.

A.S. Blair / Journal of Loss Prevention in the Process Industries 20 (2007) 523–529524

2.2. Study goals and methodology

CSB’s study objectives focused on the adequacy andenforcement of existing regulations, as well as the effec-tiveness of voluntary initiatives. Specifically, CSB sought todetermine:

1.

2

sys

Whether dust explosions are a significant problem; wasthe spike in explosions experienced in 2003 part of anoverall trend?

2.

How the Occupational Safety and Health Administra-tion (OSHA) and state governments approach prevent-ing dust fires and explosions.

3.

If MSDSs are effective in communicating dust explosionhazards.

4.

If action at the federal level is needed, to increaseawareness of the hazard and to promote the use of bestpractices to prevent and mitigate dust explosions.

3. Combustible dust incidents

CSB identified at least 281 dust fires and explosions thatoccurred in US industrial facilities from 1980 to 2005,resulting in at least 119 fatalities and 718 injuries. CSBinvestigators pulled the incident data from publicly-available sources and excluded incidents in coal minesand grain elevators. CSB also excluded transportation-related incidents and those occurring at non-industrialfacilities (such as universities, hospitals and retail facilities).

3.1. Data sources and limitations

CSB’s primary dust incident data sources included:

�

Integrated Management Information System (IMIS)database—OSHA � Fire Incident Data Organization database (NFIRS)—

National Fire Protection Association (NFPA)

� NFPA Fire Journal � Kansas State University dust incident dataNo central information source exists in the United States

for reporting all incidents and near misses.2 Most of thesources CSB consulted for dust incidents have obvious

The lack of a mandatory, nation-wide incident and near-miss reporting

tem is beyond the scope of the Combustible Dust Hazard Study.

limitations. For example, OSHA’s IMIS only includesincidents that involved fatalities, serious injuries, referralsand complaints. Employers are not required to reportincidents to OSHA that do not involve serious injuries.Also, NFIRS may not include incidents that did notinvolve outside fire department responders.Most of the data is statistical and very few sources

include detailed causal information. CSB investigatorsverified and sought additional information for as manyincidents in the data set as possible. However, CSB doesnot represent the data as complete or 100% accurate.

3.2. Incident analysis

CSB investigators defined combustible dust incidents asa fire and/or explosion—fueled by any finely divided solid

material—that caused harm to people, property, or the

environment. The incidents date from 1980 through 2005.Fires and flash fires account for about one-third of the

281 identified incidents. The remaining two-thirds of theincidents were dust explosions, or were fires that initiatedexplosions.No reliable estimate of the total financial impact of these

incidents is available. Insured losses can be hundreds ofmillions of dollars for a single incident. This does notinclude lost production, lost sales due to negative imageimpact, workers compensation and third-party lawsuitexpenses, or community economic impacts (Fig. 2).

3.3. Diversity of fuels

A wide range of fuels, from aluminum to wood dust,caused the dust fires and explosions in the CSB data set.CSB grouped the fuels into seven broad material categories(Fig. 3).

3.4. Incident trends

The data set is too incomplete to infer more than basictrends. For instance, the data is not normalized to accountfor industry growth or product production increases.However, the number of incidents per year (Fig. 4) appearsto be at least holding steady, if not increasing.Likewise, increasing trends seem to appear when we plot

the number of incidents involving each of the three most-frequently appearing fuels (food, metal and wood) (Fig. 5).

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Fig. 2. A nylon fiber explosion and fire at Malden Mills in Bethune, MA,

USA, on December 11, 1995 injured 37 people. The destruction of the

Polartec textile factory was a serious blow to the community. Rebuilding

costs and extended payroll totaled at least $425 million (US Fire

Administration, 1996).

Food

23%

Wood

24%

Metal

20%

Plastic

14%

Coal

8%

Inorganic

4%

Other

7%

Fig. 3. Distribution of combustible dust fuel types involved in 281

incidents from 1980 to 2005. (As used in this figure, ‘‘inorganic’’ refers to

inorganic combustible compounds.)

A.S. Blair / Journal of Loss Prevention in the Process Industries 20 (2007) 523–529 525

The CSB acknowledges that the apparent trends may bethe result of better incident reporting in recent years, and thedata were not normalized for production quantities ornumbers of facilities. One observation is not arguable: thenumber of dust incidents has not decreased with time, andthat spikes in the number of explosions occurred before 2003.

4. Hazard awareness

Managers, employees and safety personnel at many ofthe facilities where recent catastrophic dust explosions

occurred, were previously unaware of the dust explosionhazard. Even though West contracted a full-time cleaningcrew to vacuum and wipe up dust in the rubbercompounding area, no one at the West facility understoodthat uncleaned dust above the ceiling could explode.CTA Acoustics employees occasionally cleaned up dust

around the production lines, but they did not recognize thedust lying all around them as an explosion hazard. Eventhough workers at Hayes Lemmerz had a near miss with analuminum dust flash fire months before the fatal explosion,they did not connect the earlier event with the possibility ofa dust explosion.

4.1. Material safety data sheets

MSDS are one of the main means by which facilitymanagers and workers learn of significant safety hazards.MSDSs failed to communicate potential explosion hazardsto the employees at West and CTA.

4.1.1. West pharmaceutical services: slab dip

West Pharmaceutical Services made and molded specia-lized natural and synthetic rubber compounds. Part of theprocess involved dipping rubber strips into a slurry (called‘‘slab dip’’) of fine polyethylene powder, water andsurfactant. The slurry cooled the rubber and the poly-ethylene powder dried onto the rubber surface to preventthe strips from sticking together when they were folded.Some of the powder accumulated above a suspendedceiling in the production area.A small bulk mixing company supplied the slab dip to

West as a thick paste. In this state, slab dip was a non-toxicmaterial with no special physical hazards. However, thedried polyethylene powder was very fine (about 20 mm) andwas quite explosible. The slab dip supplier did not considerthe hazards posed by the polyethylene in its end-use state,and did not include the powder manufacturer’s dustexplosion warnings on the slab dip MSDS.

4.1.2. CTA Acoustics—phenolic resin

CTA Acoustics manufactured shaped insulationpieces for the automotive industry. Fiberglass mats wereimpregnated with a phenolic resin powder, pressed intomolds, then cured in open-flame ovens. Resin dust escapedfrom the process equipment and accumulated on floors andother surfaces in the production areas.The phenolic resin at CTA was the same material used to

make casting molds at Jahn Foundry in Springfield, MA,where a 1999 resin dust explosion killed three people andinjured nine others (USDOL, 1999). The same manufac-turer supplied the phenolic resin to both Jahn Foundry andCTA, yet the resin MSDS found at CTA (4 years after theJahn Foundry explosion occurred) did not containadequate dust explosion warnings.

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0

5

10

15

20

25

30

1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Fig. 4. Dust fires and explosions per year.

01234567

1980 1985 1990 1995 2000 2005

012345678

1980 1985 1990 1995 2000 2005

-2

0

2

4

6

8

10

12

1980 1985 1990 1995 2000 2005

Wood Dust Incidents

Food Dust Incidents Metal Dust Incidents

Fig. 5. Trends appear (dotted lines) when incidents are plotted separately for food, metal and wood dusts as fuels.

A.S. Blair / Journal of Loss Prevention in the Process Industries 20 (2007) 523–529526

4.2. MSDS survey

CSB studied the MSDSs of 140 combustible dusts inorder to determine statistically if the problem of inade-quate dust hazard communication is systemic, or limited tothe findings at the West and CTA facilities.3

Approximately 59% of the MSDSs sampled includeinformation on the explosive nature of the dust. Only 7 of140 MSDSs referenced the applicable NFPA standard formanaging dust hazards. Finally, none of the MSDSs listed

3For specifics on the MSDS survey, the reader is encouraged to consult

the CSB’s full report on the Combustible Dust Hazard Study.

physical properties of combustible dusts or explained thatdusty conditions should be avoided (to minimize secondaryexplosion potential).MSDSs written since 2000 were more likely to contain

dust explosion warnings than older MSDSs.

4.3. Improving MSDSs for combustible dust hazard

warnings

The OSHA Hazard Communication Standard4 (HCS)and American National Standards Institute (ANSI)

429 CFR 1910.1200.

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529 CFR 1910.22.629 CFR 1910.399.7Paragraph 5(a)(1) of the Occupational Safety and Health Act of 1970.8OSHA is organized into 10 regions and 73 Area Offices.9http://www.osha.gov/dts/shib/shib073105.html

A.S. Blair / Journal of Loss Prevention in the Process Industries 20 (2007) 523–529 527

standard Z400.1 contain the regulatory requirements andsuggested format, respectively, for MSDSs. However, thesetwo documents do not provide guidance for including dustexplosion warnings and combustible dust properties inMSDSs.

4.3.1. OSHA Hazard Communication Standard

The HCS requires chemical manufacturers to evaluatechemicals produced or handled in their workplace forhazards, and to convey an MSDS with the hazardouschemicals they sell. Employers must have an MSDS in theworkplace for each hazardous chemical they use, and mustcommunicate the associated hazards—through MSDSs,labeling and training—to employees who might be exposedto those hazards.

Although OSHA has stated in its interpretation lettersand compliance directives that the HCS covers combustibledusts, the text of the standard does not include dustexplosions in its definition of physical hazards, and doesnot provide any specific guidance on the type of informa-tion a combustible dust MSDS should include.

4.3.2. ANSI standard Z400.1

The HCS lists the types of information that must beincluded in an MSDS, but does not specify any particularMSDS format. In 1993, ANSI issued a universal standardfor communicating chemical hazards, ANSI Z400.1,American National Standard for Hazardous Industrial

Chemicals—Material Safety Data Sheets (ANSI, 1993).ANSI Z400.1 outlines a voluntary, consistent format for

MSDSs. It gives detailed guidance on MSDS preparation,but does not explicitly address dust explosions. Further-more, it does not define combustible dust, or address thephysical hazards associated with combustible dusts. Final-ly, the ANSI standard does not suggest information toinclude on an MSDS for combustible dust, even thoughit lists specific properties that should be includedfor flammables (e.g., flash point) or toxic chemicals(e.g., permissible exposure limit).

4.4. Inspector hazard awareness

The CSB investigations at West, CTA and Hayes revealthat all three facilities had been recently inspected by stateOSHA compliance officers and/or local fire inspectors,prior to the explosions. None of these inspectors addresseddust explosion hazards.

CSB learned, from conversations with OSHA personneland fire officials, that inspectors are typically not well-versed in or consistently trained on dust explosion hazards.The OSHA Training Institute—a main source for OSHAcompliance officer training—does not include dust explo-sion topics in its curriculum. Likewise, nearly all of thestates that CSB surveyed do not train fire inspectors oncombustible dust hazards, although a few states areimplementing training programs for combustible dusts(in response to CSB recommendations).

5. Dust fire and explosion prevention and mitigation

OSHA has not issued a regulation to prevent dust firesand explosions in general industry (including plastics,metal finishing, pharmaceuticals, etc.). The regulations forhousekeeping5 and electrical equipment6 address combus-tible dusts in a very limited manner.OSHA issued the grain facilities standard (29 CFR

1910.272) in response to a series of catastrophic grain dustexplosions that occurred in the 1970s. However, the grainfacilities standard only applies to grain elevators, grainmills and certain other grain processing facilities and doesnot apply to chemical processes or other facilities at risk fordust explosions.

5.1. OSHA enforcement programs

The OSHA General Duty Clause7 requires employers toprovide a safe and healthful workplace, free of known andrecognized hazards. OSHA has used this clause to citeemployers for failing to comply with consensus codes andstandards applicable to combustible dusts. However,OSHA has not defined a national program to inspect at-risk facilities for combustible dust hazards. Only one AreaOffice8 (Harrisburg, PA) conducts planned inspections forcombustible dust hazards, in response to a spate of dustexplosions in that area.OSHA issued a Safety and Health Information Bulletin

(SHIB) (OSHA, 2005) on combustible dust hazards in2005,9 but has not yet developed an outreach program todistribute the SHIB to at-risk companies.

5.2. NFPA standards

In lieu of regulations, consensus standards and codesprovide guidance for preventing and mitigating hazards.The NFPA provides consensus standards that addresscombustible dusts. They are voluntary unless they areadopted as law or code by a state or local jurisdiction(see Section 5.3).NFPA adopted its first combustible dust standards in the

1920s; NFPA 60 and NFPA 61 addressed dust explosionprevention in pulverized fuel systems and grain facilities,respectively. By 1950, NFPA had issued standards applic-able to plastic, aluminum, sulfur and magnesium dusts.Over the past decade, NFPA merged many of thesestandards into omnibus standards for generic classes ofcombustible particulate solids:

NFPA61

Standard for the Prevention of Fires and Dust

Explosions in Agricultural and Food Processing

Facilities (2002)

ARTICLE IN PRESSA.S. Blair / Journal of Loss Prevention in the Process Industries 20 (2007) 523–529528

NFPA484

S

1029 CFR11NFPA12Internat

tandard for Combustible Metals (2006)

NFPA654

S

E

tandard for the Prevention of Fire and Dust

xplosions from the Manufacturing, Processing,

and Handling of Combustible Particulate Solids

(2006)

NFPA655

S

E

tandard for Prevention of Sulfur Fires and

xplosions

NFPA664

S

E

tandard for the Prevention of Fires and

xplosions in Wood Processing and Woodworking

Facilities (2002)

These standards address general issues:

�

housekeeping to minimize dust accumulation, � controlling ignition sources, � equipment maintenance, � fire protection.

The standards also address equipment design and selec-tion considerations, and reference NFPA guidance fordesigning deflagration vents (NFPA 68) and explosionprotection (NFPA 69). NFPA 654 and NFPA 484 providea model for change management; hazard analysis; operat-ing, inspection; and maintenance procedures; and employeetraining programs. These elements are similar to and derivedfrom OSHA’s Process Safety Management standard.10

5.3. Fire code adoption and enforcement

OSHA has not adopted the NFPA standards pertinentto combustible dust hazards. However, many state andlocal jurisdictions in the United States have adopted theNFPA standards into their fire codes.

CSB surveyed fire code officials (typically officers in theOffice of the State Fire Marshal) in the nine states with themost dust fires and explosions in the CSB database. Inaddition, investigators compiled information from thethree states in which CSB investigated dust explosions.

The survey goals were to determine whether:

�

the states had adopted consensus standards as astatewide fire code; � state or local officials conducted planned inspections of

industrial facilities;

� state or local fire inspectors were trained on combustible

dust hazards;

� the states required operating permits for combustible

dust operations.

5.3.1. Fire code survey results

States adopt either the Uniform Fire Code11 or theInternational Fire Code,12 both of which incorporate by

1910.119.

1, Uniform Fire Code.

ional Code Council, International Fire Code.

reference the NFPA standards for combustible dust. CSBfound inconsistencies in fire code enforcement, permittingand training. Some states do not have a statewide fire code,and in most states local jurisdictions can adopt or enforcecodes independent from or in addition to the code adoptedby the state.Most surveyed states do not inspect industrial facilities

for ongoing fire code compliance or dust explosionhazards. Some inspections may occur after a complaintor a fire, and may be performed by local authorities.

6. CSB recommendations

The Chemical Safety Board approved the staff’s reporton November 9, 2006, and issued the following recom-mendations.

6.1. Occupational Safety and Health Administration

(OSHA)

1

Issue a standard designed to prevent combustible dustfires and explosions in general industry. Base the standardon current NFPA dust explosion standards (includingNFPA 654 and NFPA 484), and include at least:� hazard assessment,� engineering controls,� housekeeping,� building design,� explosion protection,� operating procedures, and� worker training.

2

Revise the Hazard Communication Standard (HCS)(1910.1200) to:� Clarify that the HCS covers combustible dusts,

including those materials that may reasonably beanticipated to generate combustible dusts throughdownstream processing or handling.� Require MSDSs to include the hazards and physical

properties of combustible dusts, as well as clearinformation on safe handling practices and referencesto relevant consensus standards.

3

Communicate to the United Nations Economic Com-mission for Europe (UNECE) the need to amend theGlobally Harmonized System (GHS) to address com-bustible dust hazards by:� defining combustible dusts,� specifying the hazards that must be addressed in

chemical information sheets, and� addressing the physical properties that must be

included on a chemical information sheet pertinentto combustible dusts.

4

Provide training through the OSHA Training Institute(OTI) on recognizing and preventing combustible dustexplosions.

5

While a standard is being developed, identify manufac-turing industries at risk and develop and implement anational Special Emphasis Program (SEP) on combus-

ARTICLE IN PRESSA.S. Blair / Journal of Loss Prevention in the Process Industries 20 (2007) 523–529 529

tible dust hazards in general industry. Include in theSEP an outreach program focused on the information inthe Safety and Health Information Bulletin (SHIB),Combustible Dust in Industry: Preventing and Mitigating

the Effects of Fire and Explosions.

6.2. American National Standards Institute Z400.1

Committee

Modify ANSI Z400.1 American National Standard forHazardous Industrial Chemicals—MSDSs to recommendthat MSDSs include information on:

�

combustible dust hazards, safe handling practices, andreferences to relevant fire codes in MSDS; � hazard information about the by-products of materials

that may generate combustible dusts due to processingor handling;

� identification of combustible dust hazards and selection

of physical properties to include in MSDS.

7. Conclusions

CSB found that combustible dusts present a serioussafety hazard in general industry. Nearly 300 incidentscaused 119 fatalities and 723 injuries in the 25-year periodbeginning in 1980. In many of the recent catastrophic dustexplosion incidents, facility personnel were unaware of thehazards of combustible dusts and had not taken steps toprevent or minimize explosions.

The OSHA Hazard Communication standard and theANSI standard for preparing MSDSs do not addresscombustible dusts or provide guidance on what informa-tion to include on the MSDS.

No current OSHA standard comprehensively addressescombustible dust hazards in the general industry. The grainfacilities standard only applies to grain elevators and grainprocessing facilities, and the Housekeeping and Electricalstandards address dusts in a very limited scope. OSHAoutreach and enforcement pertinent to combustible dusthazards is limited to an inspection program at one AreaOffice and a 2005 SHIB, for which there are no currentoutreach plans.

NFPA standards provide detailed prescriptive andperformance-based guidance for preventing and mitigatingdust fires and explosions. However, these standards arevoluntary except in those state or local jurisdictions wherethey have been adopted into fire codes. Industrial facilitiesare rarely inspected by fire code officials or required toobtain an operational permit.Based on these findings, the CSB issued a number of

recommendations to OSHA, to promulgate a new standardfor combustible dust hazard prevention, to clarify coverageof combustible dust under the hazard communicationstandard, and to perform outreach to communicate thehazard to affected employers.

Disclaimer: This paper has not been approved by theCSB and is published for general informational purposesonly. Every effort has been made to accurately present thecontents of any CSB-approved report mentioned in thispaper. Any material in the paper that did not originate in aCSB-approved report is solely the responsibility of theauthors and does not represent an official finding,conclusion, or position of CSB.

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National Standard for Hazardous Industrial Chemicals—Material

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CSB. (2004). West. Investigation Report. Dust Explosion. West Pharma-

ceutical Services, Inc., U.S. Chemical Safety and Hazard Investigation

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Explosions. CTA Acoustics, Inc./http://csb.gov/index.cfm?folder=

completed_investigations&page=info&INV_ID=35S.

CSB. (2005). Hayes. Investigation Report. Aluminum Dust Explosion.

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cfm?folder=completed_investigations&page=info&INV_ID=44S.

CSB. (2006). Investigation Report. Combustible Dust Hazard Study

/http://csb.gov/index.cfm?folder=completed_investigations&page=

info&INV_ID=53S.

OSHA. (2005). Safety and Health Information Bulletin. Combustible Dust

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