On April 4, 2009, legislation designed to protect workers from the hazards associated with combustible industrial dusts was reintroduced in the House of Representatives. H.R. 849, the "Worker Protection Against Combustible Dust Explosion and Fires Act" ("Act"), would require the Occupational Safety and Health Administration ("OSHA") to issue rules regulating combustible industrial dusts. A prior version, H.R. 5522, passed the House, but was not voted on in the Senate by the end of the last session of Congress.


The Act directs OSHA to issue interim rules related to combustible dust not later than 90 days after passage. These interim rules are very broad in their scope and apply, at a minimum, to manufacturing, processing, blending, conveying, repackaging and handling of combustible particulate solids and their dusts, including organic dusts (such as sugar, candy, paper, soap and dried blood), plastics, sulfur, wood, rubber, furniture, textiles, pesticides, pharmaceuticals, fibers, dyes, coal, metals (such as aluminum, chromium, iron, magnesium and zinc), fossil fuels and other substances. In addition, the interim rules are to require employers to conduct hazard assessments, implement comprehensive written programs, institute engineering and administrative controls, address housekeeping and implement other program requirements. The Act also requires that final rules be implemented within 18 months of enactment and that OSHA revise its Hazard Communication Standard to require the definition of "physical hazard" to include "combustible dust" as an example of such a hazard.  


Beginning in 2003, the U.S. Chemical Safety and Hazard Investigation Board ("CSB")[1] initiated a study of dust explosions in general industry. According to a report released in November 2006, the CSB determined that combustible dust explosions are a serious hazard in American industry, and existing efforts inadequately address the hazard. Among its key findings, the CSB determined that: 1) no OSHA standard comprehensively addresses combustible dust explosion hazards in general industry; 2) secondary dust explosions, due to inadequate housekeeping and excessive dust accumulations, cause much of the damage to person and property; 3) standards developed by the National Fire Protection Association ("NFPA") are effective when adopted; 4) OSHA's Hazard Communication Standard fails to address combustible dust; and 5) training for OSHA compliance officers and fire code inspectors generally does not address combustible dust hazards.

It is not uncommon for employers to fail to recognize the existence of combustible dust, or when dust accumulations subject a workplace to the potential for deflagration or explosion. According to NFPA standards, immediate cleaning of dust accumulations is warranted whenever a dust layer of 1/32 inch thickness (about the thickness of a paperclip) accumulates over a surface area of at least 5% of the floor area of the facility. Larger buildings (over 20,000 ft2) use a different formula. Dust accumulation may be on structural members, conduit and pipe racks, cable trays, floors, above ceilings and on equipment. OSHA has posted a Combustible Dust Safety and Health Topics Web page to assist employers to recognize and address hazardous combustible dust. In addition, OSHA has issued several Safety and Health Information Bulletins regarding the hazards of dust, including one addressing the potential hazards of combustible dust in industry. (SHIB 07-31-2005) In October 2007, OSHA published a directive initiating a Combustible Dust National Emphasis Program ("NEP")[2] , but withdrew it in March 2008 following a catastrophic incident involving a combustible dust explosion at a sugar refinery in which 14 workers were killed and 38 injured. At that time, OSHA issued a revised NEP under which it was increasing enforcement activities and focusing on specific industry groups that experienced either frequent combustible dust incidents or combustible dust incidents with catastrophic consequences. (CPL 03-00-008)

National Emphasis Program

The dusts OSHA identified in the March 2008 NEP include, but are not limited to: metal dust such as aluminum and magnesium, wood dust, coal and other carbon dusts, plastic dust and additives, biosolids, other organic dust such as sugar, flour, paper, soap and dried blood and certain textile materials. OSHA is stepping up its inspections and enforcement in industries and businesses that generate or otherwise handle these dusts. The target industries OSHA has indentified include: agriculture, food products, chemicals, textiles, forest and furniture products, metal processing, tire and rubber manufacturing plants, paper products, wastewater treatment, recycling operations (metal, paper and plastic) and coal handling and processing facilities.

According to the NEP, before a deflagration can occur, dust has to be combustible, dispersed in air or another oxidant, the concentration has to be at or above the minimum explosible concentration, and there must be an ignition source. Before an explosion can occur, the criteria for deflagration must be present and the combustible mixture must be dispersed within a confined enclosure without sufficient deflagration venting capacity. Compliance officers are not required to conduct air sampling. Samples of dust can be gathered and placed in plastic liter bottles for testing at OSHA's laboratory. Compliance officers are instructed to observe dust collectors and duct work, ignition control plans, housekeeping, hot work permitting programs, electrical equipment classifications and warning signs.

In situations where the facility being inspected is not a grain handling facility, but where the lab results indicate that the dust is combustible, and the combustible dust accumulations not contained within dust control systems or other containers are extensive enough to pose a deflagration, explosion or other fire hazard, then OSHA will cite the employer under its housekeeping standard (29 CFR 1910.22), or housekeeping in storage areas standard (29 CFR 1910.272). For workplaces not covered by 1910.272, but where combustible dust hazards exist within dust control systems or other containers, OSHA will generally cite employers under the General Duty Clause (Section 5(a)(1) of the OSH Act). Of course, OSHA may also cite for violations of other standards observed during the course of its investigation.