OSHA inspectors must consider a manufacturer’s or  importer’s use of information gained from actual explosion  events, lab testing, published data on similar materials or  particle size to assure they have properly classified their  products for combustible dust hazards under the revised  Hazard Communication Standard (HCS), OSHA said in a  recent guidance memorandum.

The agency’s HCS was revised to bring it into harmony  with a global standard.  Since that standard does not  contain a classification for combustible dust hazards, OSHA amended the standard's definition of “hazardous  chemical” to include combustible dust so as to maintain coverage of the hazard under its HCS. That move has put the agency in conflict with industry  stakeholders who claim inclusion of combustible dust in  the new rule amounts to backdoor rulemaking.  A lawsuit  over the agency action is currently playing out in federal  appeals court.

Marc Freedman of the U.S. Chamber of Commerce said the  memo perpetuates problems OSHA created by including  combustible dust in the standard.  He noted that the  agency did not give stakeholders a full opportunity to comment on its inclusion of combustible dust during the  HCS rulemaking.  Freedman also complained that OSHA still does not have a definition of combustible dust, yet employers are expected to identify combustible dust  hazards and train their employees about it.

“The way the memo reads, it is effectively implementing a  non-OSHA, consensus organization's definition without  the benefit of rulemaking, without a feasibility analysis,  economic analysis or examination of its effect on small  business. That's not how it's supposed to be done,” Freedman said.

In its memo, OSHA noted the HCS does not define  combustible dust.  OSHA explained that this omission  results from ongoing OSHA rulemaking on the substance  and efforts underway at the United Nations.  Instead, the  agency has provided interim guidance, including a  definition in a national emphasis program (NEP).  A  number of voluntary consensus standards, most notably  from the National Fire Protection Association (NFPA), also  provide guidance, according to the agency.

The HCS requires manufacturers and importers, called  “classifiers” in the guidance memo, to “identify and  consider the full range of available scientific literature and  other evidence concerning the potential hazards” of their  products in the form they are shipped and which might  stem from normal use and foreseeable emergencies.  There is no testing requirement.

Actual experience following a deflagration or dust explosion  often offers the best information about the product, OSHA  said.  In such cases, the product should be classified as a  combustible dust unless it can be shown conditions  surrounding the event are not expected to occur under  normal conditions of use or in foreseeable emergencies.  Absent that information, classifiers may rely upon reliable  laboratory test data.  The memo cites ASTM methods as  well as an OSHA method found in its NEP.  Another option  is published test data, such as that distributed by NFPA  and public databases, such as one from Germany called  the “Gestis-Dust-EX” database. Data may be relied upon  provided it derives from a material substantially similar to  the classifier’s product, OSHA said.  If laboratory data or  positive published test data for similar substances are  available but not used by the classifier, the inspector must  ask why, according to the guidance.

Where no test data are available or testing is inconclusive, the  classification may be based on available particle size, the  agency said.  If the material will burn and contains a sufficient  concentration of particles that would pass through No. 40 or  No. 35 sieves to create a fire or deflagration hazard, it should  be classified as combustible dust.

The guidance was not meant to be all-inclusive, since other reliable methods may be available, according to the  agency, encouraging its inspectors to consult agency  resources in those instances.  OSHA also pointed out that the guidance is not intended for downstream users.   Rather it must be applied when inspecting manufacturers  and importers, usually from referrals concerning  inadequate or inappropriate labels or safety data sheets. Companies must comply with most provisions of the rule  by June 2015.