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Definition

Aspiration is defined in the 2024 version of the OSHA Hazard Communication Standard 29 CFR 1910.1200 Appendix A paragraph A.10.1 as the entry of a liquid or solid chemical directly through the oral or nasal cavity, or indirectly from vomiting, into the trachea and lower respiratory system…Aspiration is initiated at the moment of inspiration, in the time required to take one breath, as the causative material lodges at the crossroad of the upper respiratory and digestive tracts in the laryngopharyngeal region.

An aspiration hazard involves severe acute effects such as chemical pneumonia, pulmonary injury or death occurring after aspiration of a substance or mixture. (HCS 2024, App A.10.1.1)

Additional Info

Aspiration is specific to liquids and solids which is technically different from inhalation, which is the drawing of air, gases or finely suspended and divided materials such as fumes, mists, vapors, dusts etc. into the lungs. There is obviously a middle ground somewhere between the two and both processes may occur at the same time. The HazCom Standard addresses this at 29 CFR 1910.1200 Appendix A paragraph 10.1.5.3:

The two most common aspiration hazards in consumer products are aliphatic hydrocarbons (such as gasoline, turpentine, and kerosene) and oils or fats (such as mineral or vegetable oils). Even supposedly "green" cleaning products such as those containing limonene are aspiration hazards. Isopropyl alcohol and acetone are other solvents found in both commercial and consumer products that pose an aspiration hazard.

HCS 2024: classification and labeling

OSHA adopts Aspiration Hazard Category 1, not GHS Category 2. The current requirements are in Appendix A, A.10. HCS 2024 retains the Category 1 substance criteria and makes the mixture-classification provisions more explicit:

Material	Category 1 criteria
Substances	Reliable, good-quality human evidence shows aspiration toxicity; or the substance is a hydrocarbon with a kinematic viscosity of no more than 20.5 mm2/s at 40 °C. The viscosity-based criterion applies to liquids. See A.10.2 and A.10.1.5.2.
Mixtures with suitable evidence	Use reliable, good-quality human evidence for the complete mixture, or the applicable bridging principles when sufficient information is available. See A.10.3.1 and A.10.3.2.
Mixtures classified from ingredient data	Under A.10.3.3, ingredients present at concentrations of at least 1% are relevant ingredients. Category 1 applies when the combined concentration of Category 1 ingredients is at least 10% and the mixture's kinematic viscosity is no more than 20.5 mm2/s at 40 °C. If a mixture separates into layers, classify the entire mixture in Category 1 if any layer meets both conditions. See A.10.3.3.2.

For Category 1, Appendix C, C.4.13, specifies the following label elements, along with applicable precautionary statements:

Label element	Aspiration Hazard Category 1
Pictogram	Health hazard
Signal word	Danger
Hazard statement	May be fatal if swallowed and enters airways.
Response precautions	The assigned precautions include immediately contacting a poison center/doctor if swallowed and not inducing vomiting. Follow the product's label and SDS for its complete instructions.

GHS Category 2 is not automatically an HNOC. OSHA's definition of a hazard not otherwise classified expressly excludes effects covered by a GHS hazard category OSHA has not adopted. Therefore, meeting GHS Category 2 alone does not create an OSHA requirement to classify or report that effect as an HNOC. This does not eliminate other applicable classifications or hazard-communication duties for the product.

HCS 2012 background and GHS context

Aspiration hazard became an OSHA hazard class with the 2012 revision of the Hazard Communication Standard. The archived HCS 2012 Appendix A, A.10, shows the earlier definitions and Category 1 criteria. Compare it with HCS 2024 Appendix A for the current wording and revised mixture provisions.

The 2012 rulemaking preamble explains OSHA's adoption of Category 1 rather than both GHS aspiration-hazard categories. For comparison, GHS Revision 4 describes Category 2 as covering certain substances outside Category 1, based on animal evidence and expert judgment, with a kinematic viscosity of no more than 14 mm²/s at 40 °C. Its GHS label uses Warning and “May be harmful if swallowed and enters airways.” These are not OSHA-adopted Category 2 requirements. See GHS Revision 4, Chapter 3.10, for that comparison.

The exclusion of unadopted GHS categories from the HNOC definition was also present in HCS 2012. It is not a new HCS 2024 exception.

During the 2012 rulemaking, stakeholders noted that drowning in water could be considered an aspiration hazard and suggested the term "aspiration toxicity hazard" instead. OSHA kept the term "aspiration hazard" for consistency with the GHS. As we discuss in the HNOC entry, OSHA does not consider water hazardous even though people have died from drinking too much water.

SDS Relevance

Under HCS 2024, a product classified for aspiration hazard is identified as Category 1 in SDS Section 2, with the applicable label elements described above. Do not assume that an unadopted GHS Category 2 must appear as an HNOC. Read the SDS before using the product, including Section 4 (first-aid measures) and Section 9 (physical and chemical properties), and follow the product-specific precautions. The absence of a Category 2 warning does not establish that swallowing or aspirating the product is safe.

In general, if you are working with any of the substances listed at the bottom of the last section, or any other material considered an aspiration hazard, you need to take appropriate measures such as engineering controls or personal protective equipment to reduce your risk for exposure. Risk depends on many factors including the material properties, the amounts being used, potential routes of exposure, and the procedures for handling the material in your workplace. In other words, you need to perform a risk analysis to determine your risk for exposure and the necessary steps you can take to reduce or minimize that risk.

Further Reading

• Aspiration hazard and consumer products:a review, Intl J Consumer and Product Safety, 1996, 3 (3), 153-164.
• Respiratory complications following hydrocarbon aspiration in children in Pediatr Pulmonol 2016, 51(6), 560-9.
• Petroleum jelly: Safe for a dry nose? at the Mayo Clinic.
• Aspiration Pneumonitis and Pneumonia, a medical article at the Merck Manual. A consumer-level version is also available.
• Safety evaluation and risk assessment of d-Limonene, Toxicol Environ Health B Crit Rev 2013 16(1) 17-38.

See also: emetic, hazard classification, inhalation.

Additional definitions from Google and OneLook.

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Disclaimer: The information contained herein is believed to be true and accurate, however ILPI makes no guarantees concerning the veracity of any statement. Use of any information on this page is at the reader's own risk. ILPI strongly encourages the reader to consult the appropriate local, state and federal agencies concerning the matters discussed herein.