OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

May 23, 2016

Mr. Ethan Huffer
Senior Manufacturing Engineer
Whelen Engineering Company
99 Ceda Road
Charlestown, NH 03603

Dear Mr. Huffer:

Thank you for your letter to the Occupational Safety and Health Administration's (OSHA) Directorate of Enforcement Programs. This letter constitutes OSHA's interpretation only of the requirements referenced below and may not be applicable to any question not included in your original correspondence. You requested a clarification from OSHA regarding the use of self-contained indoor dry down draft tables or benches at your facility for collection of aluminum and steel/stainless steel dust generated during grinding, buffing, and deburring operations. (OSHA uses the terms tables and benches interchangeably in this letter and considers them to be the same.) You indicated in your letter that the benches at your facility are used as follows:

  1. Restricted to only aluminum dust, with the benches clearly labeled to that effect.
  2. Cleaned at the end of every (8 hour) shift to ensure no large buildup of aluminum powder occurs.
  3. The amount collected over a shift never exceeds one ounce per bench.

Your paraphrased question and our response follow.

Question: Does OSHA permit the use of self-contained indoor dry down draft tables or benches for collection of aluminum or other metal dust (for example, steel and stainless steel) associated with grinding, buffing and deburring operations?

Response: OSHA does not have a specific standard that addresses the mitigation of fire, deflagration, or explosion hazards associated with combustible dusts. In the absence of such a standard, OSHA may enforce Section 5(a)(1) of the OSH Act, the "General Duty Clause." The General Duty Clause requires an employer to furnish to its employees a place of employment which is "free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees..." OSHA holds employers responsible for violations of the General Duty Clause if a recognized serious hazard exists in the workplace and the employer does not take reasonable steps to prevent or abate the hazard.

OSHA does not interpret or enforce National Fire Protection Association (NFPA) industry standards. However, when enforcing the General Duty Clause, OSHA may rely on industry standards, such as NFPA standards or other similar standards, as evidence showing industry recognition of a hazard and the existence of feasible means of hazard abatement. OSHA's Combustible Dust National Emphasis Program Directive provides guidance concerning reliance on NFPA standards when issuing General Duty Clause citations for deflagration, explosion or other fire hazards caused by combustible dust within a dust collection system (CPL 03-00-008, March 11, 2008).

As you note in your correspondence, the 2015 edition of NFPA 484 — Standard for Combustible Metals does not permit indoor dry-type dust collectors for aluminum (NFPA 484 § In addition, NFPA 484 prohibits self-contained dry down draft benches for the collection of combustible metals (NFPA 484 § These NFPA standards provide evidence of industry awareness that a combustible dust hazard may exist when using this type of equipment. The employer must ensure that engineering and administrative controls are sufficiently effective and robust to materially reduce or prevent such hazards. Maintaining low levels of combustible dust accumulation through frequent cleaning to ensure no significant buildup of metal dust in the benches may be one approach to controlling this hazard.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA sets requirements by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time letters are affected when OSHA updates a standard, a legal decision impacts a standard, or changes in technology affect an interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at https://www.osha.gov. If you have further questions, please contact the Office of Chemical Process Safety and Enforcement Initiatives at (202) 693-2341.



Thomas Galassi, Director
Directorate of Enforcement Programs