Now, moving through the classes in order — Page 227, Lesson 332

I want to walk you through the hazard labels used for the transport of dangerous goods by air. These labels are the visual coding system that tells everyone handling a package exactly what kind of risk it presents. Let's start with the overall structure you see at the top. The word "Orange" here refers to the place for division and compatibility group — that's a specific field on the label where the numerical division and, for explosives, the compatibility group letter are printed. The note underneath is critical: packages bearing this label with the marking "Division 1.1" or "Division 1.2" are not normally permitted for transport by air. Those are the most violently explosive categories, and they're essentially banned from passenger and cargo aircraft except under very rare special permits. Now, moving through the classes in order. Class 2 is Gas Flammable. The symbol is a flame, and it can be black or white on a red background. That red background is your immediate visual cue — red means fire risk. Next, Class 2 Gas Toxic. The symbol is a skull and crossbones in black, on a white background. That tells you the gas is poisonous if inhaled. Then Class 2 Gas Non-flammable. The symbol is a gas cylinder in white on a green background. Green signals that while the gas isn't burning, it's still under pressure and could cause asphyxiation or a physical rupture hazard. Class 3 is Liquid Flammable. Again, the symbol is a flame, black or white, on a red background. Red for flammability. Class 4 has several subclasses. First, Solid Flammable — symbol is a flame in black on a background that is white with seven vertical red stripes. Those stripes are distinctive — you won't confuse it with the liquid flammable label. Next, Class 4 Spontaneous Combustion. Symbol is a flame in black, background is upper half white, lower half red. The split tells you this material can ignite on its own without an external ignition source. Then Class 4 Danger If Wet. Symbol is a flame, black or white, on a blue background. Blue means water-reactive — if this gets wet, it can produce flammable gases or heat that causes ignition. Now Class 5.1 — Oxidizer. The symbol is a flame over a circle in black, on a yellow background. The figure '5.1' must appear in the bottom corner. Oxidizers don't burn themselves, but they supply oxygen to make other fires burn more fiercely. Class 5.2 — Organic Peroxide. The symbol is a flame, black or white, on a background that is upper half red, lower half yellow. The figure '5.2' goes in the bottom corner. Organic peroxides are both flammable and chemically unstable — they can decompose explosively. Class 6 — Toxic. Symbol is a skull and crossbones in black on a white background. Same as the toxic gas label, but for solids or liquids that are poisonous by ingestion, skin contact, or inhalation. Class 6 — Infectious. The symbol is three crescents superimposed on a circle in black on a white background. The figure '6' goes in the bottom corner. And there's a mandatory inscription on the bottom part of the label: "INFECTIOUS SUBSTANCE - in case of damage or leakage immediately notify public health authority". That's not optional — it must be printed on the label. Finally, Class 7 — Radioactive. This is the Category II — Yellow label. The symbol is a trefoil in black. The background is top half yellow with a white border, bottom half white. In the bottom half, in black text, you must have the word "Radioactive", then "Contents....." and "Activity....." as blank fields to be filled in, and inside a black outlined box the words "Transport Index". Two red vertical stripes must follow the word "Radioactive". Those stripes indicate the radiation level — two stripes means Category II, which is an intermediate radiation hazard. That covers the full set of hazard labels you need to recognize. Each one is a precise code — symbol, colour, text, and figure number — that tells you exactly what danger is inside the package.