What is Hazmat Shipping?

Originally posted September 24, 2024, updated September 29, 2025.

Shipping a pallet of lithium-ion batteries or a drum of industrial cleaning chemicals isn’t the same as shipping t-shirts. These are hazardous materials, hazmat for short, and they demand a higher level of caution.

Unlike standard freight, hazmat shipments carry risks that can endanger people, property, and the environment if not handled properly. That’s why hazmat shipping is tightly regulated, with federal laws and carrier requirements dictating exactly how dangerous goods must be classified, packaged, labeled, and transported. For shippers, understanding and following these rules protects supply chains and ensures safety from warehouse to final delivery.

Hazardous materials are divided into nine classes internationally, depending on their risk level and the dangerous goods involved. The hazardous materials table is presented like this:

Hazardous material classes

Class	Description	Divisions	Examples
Class 1 – Explosives	Materials that can combust or explode when exposed to high heat or a chemical reaction. Air transportation is not permitted.	1.1: Mass explosion hazard 1.2: Projection hazard 1.3: Minor blast/projection hazard 1.4: Minor explosive hazard 1.5: Very insensitive mass explosion hazard 1.6: Extremely insensitive mass explosion hazard	Fireworks, ammunition, blasting agents
Class 2 – Gases	Gases under pressure (vapor pressure ≥ 300 kPa at 50°C or gaseous at 20°C). Restricted to ground transport.	2.1: Flammable gases 2.2: Non-flammable gases 2.3: Toxic gases	Propane, helium, chlorine
Class 3 – Flammable liquids & combustible liquids	Liquids that ignite at low temperatures and cause severe fires.	–	Gasoline, acetone, ethanol
Class 4 – Flammable solids	Solids that ignite and burn easily.	4.1: Flammable solids 4.2: Spontaneously combustible 4.3: Dangerous when wet	Matches, magnesium, sulfur
Class 5 – Oxidizing substances & organic peroxides	Materials that release oxygen and support combustion.	5.1: Oxidizing substances 5.2: Organic peroxides	Hydrogen peroxide, ammonium nitrate fertilizers
Class 6 – Toxic & infectious substances	Materials that can cause injury or death if inhaled, swallowed, or exposed.	6.1: Toxic substances 6.2: Infectious substances	Cyanide, medical waste
Class 7 – Radioactive materials	Emit ionizing radiation greater than 0.002 microcuries per gram.	–	Uranium, plutonium, medical isotopes
Class 8 – Corrosives	Acids and alkalis that cause severe damage to tissue, metals, or materials.	–	Sulfuric acid, sodium hydroxide
Class 9 – Miscellaneous dangerous goods	Hazards not covered elsewhere, including environmentally hazardous or temperature-sensitive materials.	–	Lithium batteries, dry ice

How is hazmat shipping regulated?

Shipping hazardous materials is managed by several sets of regulations that set out the rules to ship dangerous goods domestically and internationally. This covers:

• Acceptable shipping methods.
• Appropriate packaging.
• Labeling requirements.
• Training requirements for staff handling hazmat shipments.

U.S. Department of Transportation (Title 49 CFR)

Title 49 manages the shipping of hazardous materials within the United States, and is the most important set of federal regulations for be aware of when hazmat shipping domestically. 49 CFR covers the following:

• How to properly classify hazardous materials.
• The quantity of hazardous materials permitted in each package.
• The packaging/packing group is required for different hazardous materials shipments.
• Required documentation, labeling, and training requirements.

IMDG (International Maritime Dangerous Goods)

The IMDG code covers the shipping regulations for sending hazardous materials by sea across international borders and how to protect the environment and workers from severe injury.

ICAO / IATA

The International Civil Aviation Organization (ICAO) heads up the standards for the transportation of hazardous materials by air. The International Air Transport Association (IATA) is the counterpart for private-sector standards, including hazmat shipping via commercial airlines.

Hazmat shipping requirements by carrier

Hazmat shipping rules don’t just vary by material type, they also differ by carrier. Each carrier has its own certification process, paperwork, and list of prohibited items that shippers must follow to stay compliant. Below is an overview of the requirements for UPS, FedEx, and USPS when it comes to handling hazardous materials.

UPS hazmat shipping

To ship hazardous materials using UPS, shippers must have a UPS user name and shipping account and comply with all carrier restrictions and items on the Hazardous Materials Agreement Checklist. Items that are prohibited from shipping hazardous materials with UPS include:

• Fireworks
• Hazardous waste
• Human remains
• Marijuana

FedEx hazmat shipping

FedEx offers ground shipments for hazardous materials. First, all hazmat shippers must be certified by FedEx to ship hazardous materials and be compliant with the FedEx Ground Hazardous Materials Shipping Guide, which includes:

• Packaging and preparing hazardous goods under 49 CFR.
• Providing a copy of the special permit paperwork to the FedEx Ground facility accepting your shipment, if shipping under a U.S. Department of Transportation (DOT) special permit.
• Providing the Material Safety Data Sheet (MSDS) upon request.

Note that FedEx Ground for hazmat shipping is not available in Alaska, Hawaii, or Canada.

USPS hazmat shipping

USPS only ships certain classes of hazardous materials, which can be found at Domestic Shipping Prohibitions & Restrictions and International Shipping Prohibitions & Restrictions. It’s important to check these restrictions closely to prevent hazmat shipments from being rejected. Prohibited materials for domestic shipments include:

• Air Bags
• Ammunition
• Explosives
• Gasoline
• Liquid Mercury
• Marijuana

How to ship hazardous goods correctly

Handling hazardous goods is critical, otherwise shipments can be delayed, rejected, or even lead to fines and safety risks. With strict regulations in place, shippers need to follow proper packaging, labeling, and documentation requirements at every step. Here’s how to ship hazmat materials correctly to stay compliant and keep your supply chain moving safely.

Understand the regulations

Before you begin hazmat shipping, you must understand what your obligations are as a shipper and which applicable regulations to be aware of. Title 49 CFR is the most important domestic regulation for hazmat shipping, but there are others that may apply in the case of international air shipping of hazardous materials. Familiarizing yourself with these regulations, even if you are outsourcing to a 3PL, means you are more likely to avoid costly errors in shipping.

Determine the class of hazardous material

Shipping hazardous materials correctly means understanding what class of dangerous goods is involved with each shipment. This will give you guidance on what shipping methods are available, what packing group to use, and what labeling is required for a compliant shipment. The Safety Data Sheet (SDS) for that hazardous material will provide the proper shipping name, hazard class, and Identification Number.

It’s important to note that in some cases, a shipment could feature more than one hazard class. When this happens, make sure you consult the appropriate dangerous goods regulations.

Select the right packaging

That are distinct packing groups involved with shipping hazardous materials, according to what is being shipped and how much risk is involved. Under Title 49, there are three main packing groups for hazmat shipments:

• Packing Group I: Great Danger 
• Packing Group II: Medium Danger 
• Packing Group III: Minor Danger

Follow the labeling requirements

All hazmat shipments need to be labeled to communicate how they need to be handled in transit. A hazmat shipping label may communicate how the package needs to be carried, any particular hazards, or handling requirements i.e. being kept away from heat.

Provide the necessary documentation

Hazmat shipping requires more shipping papers than a typical domestic or international shipment. Depending on the shipping carrier you are using, you need to prepare to share information such as:

• UN identification number for the hazardous material
• The proper shipping name
• The hazard class
• The packing group
• Quantity, number, and type of packages
• Certification for hazmat shipping with that carrier

The importance of proper warehousing for hazmat

Safe hazmat shipping starts long before a package is loaded onto a truck. Correct warehousing practices are just as critical, ensuring hazardous materials are stored, handled, and tracked in compliance with strict federal and carrier regulations. Working with an experienced 3PL partner provides the added benefit of specialized expertise in hazmat or chemical warehousing, inventory management, and regulatory requirements. Many 3PLs also work with their customers to conduct a chemical compliance audit to identify risks, close gaps, and confirm that facilities meet safety standards, helping shippers avoid costly penalties and keep operations running smoothly from storage through final delivery.

How WSI manages hazmat shipping

Shipping hazmat materials is complicated. WSI simplifies the process with a dedicated compliance team that reviews each product to ensure adherence to carrier-specific guidelines. With a commitment to the highest of safety standards, including participation in the Responsible Care® program, WSI exceeds regulatory requirements and safeguards stakeholders.

• WSI’s storage solutions are compliant with DOT, EPA, DHS, OSHA standards, ensuring safekeeping of chemicals with full site containment.
• Our team of specialists has handling certifications like IMDG, IATA, DOT, and HAZWOPER to manage chemicals safely, from inbound logistics to distribution.
• From fire rooms to cold storage rooms, each of WSI’s 4 hazmat facilities are equipped with the specific needs of temperature-sensitive substances, ensuring product integrity.

Looking for more information about WSI’s chemical storage and hazmat warehousing? Contact us today to speak with one of our friendly fulfillment experts.

1. https://www.phmsa.dot.gov/standards-rulemaking/hazmat/hazardous-materials-regulations ↩︎