DOT Aims to Sync U.S. Hazardous Materials Rules with Global Standards
Published Date: 2/10/2026
Proposed Rule
Summary
The Department of Transportation wants to update hazardous materials rules to match international standards. This means changes in how dangerous goods are named, packed, and shipped, making things safer and cheaper for businesses and travelers in the U.S. You’ve got until April 13, 2026, to share your thoughts before the new rules take shape.
Analyzed Economic Effects
14 provisions identified: 8 benefits, 4 costs, 2 mixed.
Harmonize HMR with International Rules
PHMSA proposes changing U.S. hazardous materials rules to match international standards (including the 2025-2026 ICAO Technical Instructions, Amendment 42-24 to the IMDG Code, and the 23rd revised UN Model Regulations). The agency says these changes are intended to reduce delays and lower costs to entities or individuals in the United States and promote the free flow of commerce.
Larger Limited-Quantity Gas Shipments
PHMSA proposes allowing four Division 2.2 compressed gases (UN1006 Argon, UN1013 Carbon dioxide, UN1046 Helium, UN1066 Nitrogen) to be transported as limited quantity materials in amounts up to 1000 ml (34 fluid ounces) per package for modes other than air when in DOT specification cylinders or UN pressure receptacles. This would extend limited-quantity relief for those gases outside of air transport.
TMAH Reclassification and Packaging Changes
PHMSA proposes multiple changes for Tetramethylammonium hydroxide (TMAH), including a new Hazardous Materials Table entry for aqueous solutions, revised hazard classifications and proper shipping names for PG II/III solutions (UN1835), reclassification of TMAH solids (UN3423), two new special provisions, and revised packaging authorizations. These changes reflect new incident and test data showing a toxicity hazard in addition to corrosivity.
Sodium-Ion Batteries Regulated Like Lithium
PHMSA proposes adding Hazardous Materials Table entries and transport provisions that regulate sodium ion batteries in the same way as lithium ion batteries, to reflect their anticipated increased use as an alternative to lithium-ion batteries.
Air Shipments: 30% Battery State-of-Charge Limit
PHMSA proposes expanding state-of-charge limits for certain lithium and sodium ion batteries transported by air, capping stored energy at 30 percent or less of the battery's capacity at the time of transport.
Conditions for Ammonium Nitrate Solutions
PHMSA proposes adding specific conditions (based on concentration, water content, combustible material content, chlorine content, pH level, and temperature) under which hot concentrated solutions of ammonium nitrate can be transported under UN2426 or qualify for an exception from the HMR.
No Adoption of Stricter Charcoal Rules
PHMSA is not proposing to adopt Amendment 42-24 IMDG Code changes that would remove the ability to use UN Test N.4 to except some carbon materials and would add testing and stowage requirements. PHMSA says adopting those IMO provisions could unduly burden manufacturers and is not necessary given the lack of domestic incidents.
No New Labels for Battery Vehicles Now
PHMSA is not proposing to adopt Special Provision 405 (from the UN Model Regulations / IMDG) that would require additional marking and labeling for battery-powered vehicles when fully enclosed by packaging. PHMSA cites concerns that this would mean new marks/labels on many consumer goods (e.g., lawn mowers, scooters) and seeks more evaluation.
New Standards Incorporated by Reference
PHMSA proposes to incorporate by reference updated international and ISO standards into the HMR, including the 2025-2026 ICAO Technical Instructions, Amendment 42-24 to the IMDG Code, the 23rd revised UN Model Regulations, and several updated ISO standards (e.g., ISO 9809-4:2021, ISO 11114-1:2020). Some referenced documents are free (UN materials); others must be purchased.
Temporary Enforcement Discretion in Effect
PHMSA issued a December 9, 2024 notice of enforcement discretion that remains in effect: PHMSA and other federal enforcing agencies will not take enforcement action against offerors or carriers who follow the 2025-2026 ICAO Technical Instructions for air or Amendment 42-24 IMDG Code for vessel transport during this rulemaking. For rail and highway, agencies will not enforce against offerors or carriers following the international standards provided appropriate emergency response information accompanies the shipment.
Organic Peroxides Authorized Without Approval
PHMSA proposes edits to the organic peroxides table (49 CFR 173.225) to add three new organic peroxide formulations that would be authorized for transportation without prior approval. That would let shippers move those listed formulations without seeking case-by-case approvals.
More Specific Lithium Battery Emergency Info
PHMSA proposes to amend Special Provision 389 so that emergency response information for UN3536 (lithium batteries installed in cargo transport units) must identify the predominant battery type installed (e.g., lithium ion or lithium metal) and provide immediate methods for handling fires.
Rapid-Test Nitrocellulose Filter Exception
PHMSA proposes a new special provision to except 'UN3270, Nitrocellulose membrane filters, with not more than 12.6% nitrogen, by dry mass'—used in rapid test devices and bioanalytical tests—from regulation when specific packaging requirements are met.
New Information-Collection Requirements
PHMSA says this NPRM proposes new information collection requirements tied to the HMR and proposes to revise the OMB control number table in 49 CFR 171.6 to list the relevant sections where those new collections are specified.
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Key Dates
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