Which methods are used for affixing UN Identification Numbers?

• A. Red banners
• B. Circular blue stickers
• C. Rectangular orange panels and diamond-shaped hazard classification system placards
• D. Warnings on the label only

Answer: (C)

UN Identification Numbers are four-digit codes used to identify hazardous substances during transport, and they must be clearly posted in places where responders can see them quickly. The standard ways to affix these numbers are on rectangular orange panels and on diamond-shaped hazard classification placards. Rectangular orange panels are mounted on the sides of vehicles carrying hazardous materials and display the UN number along with hazard information, while diamond-shaped placards (the common hazard classification signs) also carry the UN number and hazard details to ensure rapid recognition from multiple angles. Other options don’t fit because red banners aren’t the established signaling method for UN IDs, circular blue stickers aren’t used for this purpose, and relying on warnings on a label alone doesn’t guarantee visibility or standardization across different carriers and situations.