When is a UN number required on the shipping paper?

• A. When the material is colored red
• B. When the material has a UN number or when the HMR requires one
• C. Only for solids
• D. Only for consumer products

Answer: (B)

The UN number on a shipping paper is required whenever the material has a UN designation or when the Hazardous Materials Regulations require one. That four-digit code acts as the universal identifier for a specific hazardous substance or material family, so listing it ensures precise, consistent identification across carriers and fields like emergency response. If a material has a UN number, it must appear on the shipping paper; likewise, there are regulatory scenarios where the HMR requires a UN number to be listed even if you might not expect it for that substance. Color, state of matter, or whether a product is consumer-oriented do not determine UN-number requirements—the need comes from how the material is identified as hazardous. For example, a flammable liquid with UN 1993 must include UN 1993 on the shipping paper along with its proper shipping name and hazard class.