Frequently Asked Questions
Safety Data Sheets
(GHS) Globally Harmonized System of Classification
and Labeling of Chemicals
Please note that OSHA maintains the most up-to-date information on GHS and may have a more
comprehensive list of the latest frequently asked questions. Please visit OSHA for more information.
How has OSHA addressed hazards covered under the current Hazard Communication
Standard that have not been addressed by the GHS?
In the Notice of Proposed Rulemaking (NPRM), OSHA proposed to include hazards currently covered under the Hazard
Communication Standard (HCS) that have yet to be addressed by the GHS (OSHA provided several examples: simple
asphyxiants, and combustible dust) in a separate category called "Unclassified Hazards". In response to comments
from the regulated community, OSHA has renamed the category to "Hazards Not Otherwise Classified (HNOC)" to
minimize confusion. In the final HCS, HNOC hazards will not be required to be disclosed on the label but will be
required to be disclosed in section 2 of the Safety Data Sheet (SDS). This reflects how GHS recommends these
hazards should be disclosed. Chemical manufacturers and importers are expected to assess these hazards when they
are conducting their hazard evaluation of physical and health hazards. A new or separate evaluation is not
required. Also in the final standard, in response to comments, OSHA has removed pyrophoric gases, simple
asphyxiants, and combustible dust from the HNOC hazard category and has addressed these chemicals individually (see
question below for more information on each hazard).
How has OSHA addressed pyrophoric gases, simple asphyxiants, and combustible
In the revised Hazard Communication Standard (HCS), OSHA has added pyrophoric gases, simple asphyxiants and
combustible dust to the definition of "hazardous chemical". OSHA has also added definitions to the revised HCS
for pyrophoric gases and simple asphyxiants, and provided guidance on how to define combustible dust for the
purposes of complying with the HCS.
- Pyrophoric gases:
OSHA has retained the definition for pyrophoric gases from the current HCS. Pyrophoric gases must be
addressed both on container labels and SDSs. OSHA has provided label elements for pyrophoric gases which
include the signal word "danger" and the hazard statement "catches fire spontaneously if exposed to
- Simple asphyxiants:
OSHA has revised the definition of simple asphyxiants that was proposed in the Notice of Proposed
Rulemaking (NPRM) as a result of comments from the regulated community. In the final HCS, simple
asphyxiants must be labeled where appropriate, and be addressed on SDSs. OSHA has provided label elements
for simple asphyxiants which include the signal word "warning" and the hazard statement "may displace
oxygen and cause rapid suffocation".
- Combustible dust:
OSHA has not provided a definition for combustible dust to the final HCS given ongoing activities in the
specific rulemaking, as well as in the United Nations Sub-Committee of Experts on the GHS (UN/SCEGHS).
However, guidance is being provided through existing documents, including the Combustible Dust National
Emphasis Program Directive CPL 03-00-008, which includes an operative definition, as well as provides
information about current responsibilities in this area. In addition, there are a number of voluntary
industry consensus standards (particularly those of the NFPA) that address combustible dust.
In the final HCS, combustible dust hazards must be addressed on labels and SDSs. Label elements are provided
for combustible dust in the final HCS and include the signal word "warning" and the hazard statement "May form
combustible dust concentrations in the air".
For chemicals in a solid form that do not present a combustible dust hazard, but may form combustible dusts
while being processed in normal downstream uses, paragraph (f)(4) of the HCS allows the chemical manufacturer
some flexibility in labelling requirements. The manufacturer or importer to may transmit the label to the
customer at the time of the initial shipment, but the label does not need to be included with subsequent
shipments unless it changes. This provides the needed information to the downstream users on the potential
hazards in the workplace, while acknowledging that the solid metal or other materials do not present the same
hazards that are produced when these materials are processed under normal conditions of use.
I understand that the United Nations revises the GHS every two years.
How will OSHA manage and communicate changes to the Hazard Communication
It is expected that the GHS will be a living document and is expected
to remain up-to-date and relevant; therefore further changes may be adopted on a two year cycle.
Presently most of the recent updates have been clarification of text. However, OSHA anticipates
that future updates of the Hazard Communication Standard (HCS) may be necessary and can be done
through various rulemaking options, including:
- Technical updates for minor terminology changes,
- Direct Final Rules for text clarification, and
- Notice and Comment rulemaking for more substantive or controversial
updates such as additional criteria or changes in health or safety hazard classes or