Who Is Affected by the HCS 2024 Update
Any organization that manufactures, imports, distributes, or uses hazardous products is in scope. This includes manufacturing, healthcare, construction, transportation, laboratories, and service providers that handle chemicals. Smaller businesses without dedicated regulatory teams are affected too, but the rule includes flexibilities that help reduce the compliance burden while preserving worker protection.
Major Changes to Hazard Classification
Aerosols
The class formerly called Flammable Aerosols is now Aerosols. It includes a new category for non-flammable aerosols. The renaming and added category improve precision for classification, labeling, and downstream training.
Chemicals Under Pressure
A new class covers solids and liquids that are pressurized by a gas. It is distinct from aerosols. OSHA notes these products are often supplied in refillable containers, which can lead to different use patterns and risk profiles.
Flammable Gases
HCS 2024 expands the class into Categories 1A, 1B, and 2. Category 1A now contains four subcategories to clarify behavior and controls:
- Category 1A – Flammable: Strictest flammability criteria under normal conditions; controls include ventilation, ignition source control, and leak detection.
- Category 1A – Pyrophoric: Can ignite spontaneously in air at or below 54.4 °C; handling usually requires inerting, specialized equipment, and emergency isolation procedures.
- Category 1A – Chemically Unstable Gas A: Can react or decompose at normal temperature and pressure; storage stability, temperature control, and system design are critical.
- Category 1A – Chemically Unstable Gas B: May be stable at ambient conditions but become unstable under elevated temperature or pressure; procedures must address temperature rise, compression, and upset scenarios.
Desensitized Explosives
A new class for explosives treated to reduce or eliminate explosive properties for safer handling and transport. Classification and label elements communicate residual risks when the desensitizing agent is removed or the product is concentrated.
Safety Data Sheet (SDS) Updates
Section 9 – Physical and Chemical Properties
OSHA revised required and optional properties to improve decision-making. Some items, such as odor threshold, are no longer mandatory. New required data points include particle characteristics and other properties that better represent real-world behavior and help users set controls.
Section 3 – Trade Secrets and Ingredient Declaration
Where ingredient composition is protected as a trade secret, the SDS must include in Section 3 a unique product identifier and its source. This preserves confidentiality while providing traceability for emergency response, medical management, and regulatory inquiries.
Supplier Information Requirements
OSHA clarified that the original supplier’s U.S. address and phone number must appear on the SDS, with corresponding expectations for labels, to ease escalation and verification.
Labeling Changes Under HCS 2024
Core Labeling Elements
- Signal Words (“Danger” or “Warning”) indicating relative severity for the highest applicable hazard category.
- Pictograms that match the classified hazards only; avoid redundant or non-applicable symbols.
- Hazard Statements using the precise regulatory text for each category, consistent with the SDS.
- Precautionary Statements for safe handling, storage, and emergency actions; combine or rationalize where OSHA permits to maintain readability.
Small and Very Small Containers
Small containers (≤ 100 mL) may use reduced labeling. Very small containers (≤ 3 mL) may use further reduced labeling. Where space is limited, fold-out labels or attached tags are allowed provided key information remains available. OSHA also reinforces the need to include a U.S. address on labels, consistent with the SDS rule.
Other Forms of Warning and SDS Availability
Employers must ensure SDSs are readily accessible to employees at all times. When new hazard information emerges, documents and labels must be updated promptly so training and workplace controls remain accurate.
Transition Periods and Compliance Deadlines
Deadlines for Substances
- Labels and SDSs updated by January 19, 2026.
- Employer training & workplace labels/programs updated by July 19, 2026.
Deadlines for Mixtures
- Labels and SDSs updated by July 19, 2027.
- Employer training & workplace labels/programs updated by January 19, 2028.
Transition Timeline Summary
HCS 2024 Transition Timeline
| Product Type |
Labels & SDSs Updated By |
Employer Training & Workplace Labels Updated By |
| Substances |
January 19, 2026 |
July 19, 2026 |
| Mixtures |
July 19, 2027 |
January 19, 2028 |
Practical Impact on U.S. Operations and Global Trade
U.S. Operations
Organizations will need to adjust classification documentation, regenerate SDSs with updated Sections 3 and 9, redesign labels, and update training content to reflect new and revised hazard classes. Small and very small container rules reduce space pressure on packaging while preserving critical information. Expect updates to change control, artwork systems, supplier onboarding, and ERP fields used for SDS and label data.
International Alignment
Because the update aligns with the GHS, companies selling in multiple regions can work from more consistent SDSs and labels. Even in markets still transitioning from earlier GHS revisions, the clarified U.S. approach can guide planning and reduce duplicated work. Global harmonization lowers the need for market-specific variants and eases multilingual training.
OSHA HCS 2024 Compliance Checklist
Classification and SDS Work
- Review every product for changes in hazard class (Aerosols, Chemicals Under Pressure, Flammable Gases, Desensitized Explosives).
- Update SDS Section 9 (revised properties, particle characteristics, etc.).
- Update SDS Section 3 processes to capture a unique identifier and source for trade secret cases.
- Validate that a U.S. supplier address and phone number appear on SDSs.
Labeling
- Implement reduced-content labels for small and very small containers where applicable.
- Confirm presence and correctness of signal word, pictograms, hazard statements, and precautionary statements.
- Verify a U.S. address on labels to match SDS requirements.
- Use fold-out or attached tags when space is limited, maintaining traceability.
Training and Program Updates
- Refresh hazard communication programs to reflect new classes and revised definitions.
- Update employee training materials and deliver training before the deadlines.
- Ensure SDS access methods are reliable and auditable.
Change Control and Rollout
- Pilot updates on a focused set of SKUs to validate templates, data fields, and print constraints.
- Maintain version histories for SDSs and labels.
- Schedule periodic reviews to catch missed products or late data updates.
OSHA Penalties and Enforcement Updates for 2025
Current Maximums and Annual Adjustments
OSHA adjusts civil penalties each year for inflation. For 2025:
- Maximum for serious and other-than-serious violations: USD 16,550 per violation.
- Maximum for willful or repeat violations: USD 165,514 per violation.
- Failure to abate: USD 16,550 per day after the abatement date.
Include these figures in internal compliance communications and refresh them annually to avoid outdated guidance.
Kalium Solutions: Your Partner in Preparing for Compliance with Confidence
The HCS 2024 update is significant, but a structured rollout keeps the work manageable. Start with classification and SDS templates, move to labeling and small-container strategy, then finish with employee training and program updates. A staged approach protects workers, reduces risk, and positions your organization for smoother global compliance.
Take the Next Step Toward Full HCS 2024 Compliance
Need help updating SDSs, redesigning labels, or training your teams? Kalium Solutions offers training, turnkey services, and software support to streamline HCS 2024 compliance.
Contact Us
FAQs About the OSHA HCS 2024 Update
What is the OSHA HCS 2024 update and why was it issued?
OSHA updated the Hazard Communication Standard on July 19, 2024 to improve hazard clarity, reduce incidents, and better align U.S. requirements with the Globally Harmonized System. The rule primarily aligns with GHS Revision 7 and references selected elements consistent with Revision 8 where OSHA incorporated them.
Which GHS revision does the 2024 HCS align with?
Primarily GHS Revision 7, with some elements consistent with Revision 8 reflected in OSHA’s changes.
Who is affected by the HCS 2024 changes?
Manufacturers, importers, distributors, and employers that handle hazardous products across sectors such as manufacturing, healthcare, construction, transportation, and laboratory settings. Small and mid-sized businesses are in scope as well.
What new or revised hazard classes should I know first?
Two new classes were added: Chemicals Under Pressure and Desensitized Explosives. The Aerosols class was renamed from Flammable Aerosols and now includes a non-flammable category. Flammable Gases expanded to Categories 1A, 1B, and 2, with Category 1A subdivided into Flammable Gas, Pyrophoric Gas, Chemically Unstable Gas A, and Chemically Unstable Gas B.
How did the classification of flammable gases change exactly?
The standalone Pyrophoric Gases class was removed and integrated as a subcategory within Flammable Gases. The class now consists of Categories 1A, 1B, and 2. Category 1A has four subcategories: Flammable Gas, Pyrophoric Gas, Chemically Unstable Gas A, and Chemically Unstable Gas B.
What changed in Safety Data Sheets, especially Section 9?
Section 9 requirements were revised. Some properties that were previously mandatory, such as odor threshold, are no longer required, while new data points such as particle characteristics are now required to improve decision-making.
What are the new trade secret rules for SDS Section 3?
If composition is confidential for trade secret reasons, the SDS must include a unique product identifier and its source in Section 3. This preserves confidentiality while improving traceability for users and responders.
What supplier information must appear on SDSs and labels?
OSHA clarified that the original supplier’s U.S. address and phone number must be listed on SDSs and reinforced the same expectation for labels to support quick contact and verification.
What are the labeling rules for small and very small containers?
Reduced labeling is allowed for small containers of 100 mL or less, with further reductions for very small containers of 3 mL or less. Where space is limited, fold-out labels or attached tags can be used to keep essential information available. The U.S. address requirement on labels still applies.
What are the transition deadlines for substances and mixtures?
For substances: labels and SDSs by January 19, 2026; employer training and workplace labeling by July 19, 2026.
For mixtures: labels and SDSs by July 19, 2027; employer training and workplace labeling by January 19, 2028.
The overall transition spans roughly 18 to 42 months, depending on product type and stakeholder roles.
How do these changes affect employer training and workplace programs?
Employers must update hazard communication programs, workplace labels, and training to reflect the new and revised hazard classes and SDS content. Training should be delivered in time to meet the applicable deadlines for substances and mixtures.
