How many main classes of dangerous goods are defined in IATA DGR, and what are they?

• A. Nine classes: 1 Explosives; 2 Gases; 3 Flammable liquids; 4 Flammable solids; 5 Oxidizing substances and organic peroxides; 6 Toxic and infectious substances; 7 Radioactive material; 8 Corrosive substances; 9 Miscellaneous dangerous goods.
• B. Eight classes: 1 Explosives; 2 Gases; 3 Flammable liquids; 4 Flammable solids; 5 Oxidizing substances; 6 Toxic substances; 7 Radioactive; 8 Corrosive; 9 Biological hazards; 10 Miscellaneous.
• C. Nine classes: 1 Explosives; 2 Gases; 3 Flammable liquids; 4 Corrosive substances; 5 Toxic substances; 6 Radioactive; 7 Biological hazards; 8 Environmental hazards; 9 Miscellaneous.
• D. Nine classes: 1 Explosives; 2 Gases; 3 Flammable liquids; 4 Flammable solids; 5 Organic peroxides; 6 Toxic substances; 7 Radioactive; 8 Corrosive; 9 Toxicological.

Answer: (A)

The main idea here is that air-transport hazardous goods are grouped into a fixed set of nine classes in the IATA Dangerous Goods Regulations. This classification system provides a consistent way to identify hazards, guide packaging and labeling, and train staff.

The nine classes are: explosives; gases; flammable liquids; flammable solids; oxidizing substances and organic peroxides; toxic and infectious substances; radioactive materials; corrosive substances; and miscellaneous dangerous goods. This structure is used because it covers the broad ways in which dangerous goods can pose risk during transport, from explosive energy or flammable behavior to toxicity, radioactivity, or corrosivity, with a catch‑all category for items that don’t fit other classes.

In this framework, infectious substances are not a separate class; they sit under the toxic and infectious substances category. Organic peroxides are not a stand-alone class either; they’re included with oxidizing substances in the same class. There isn’t a separate environmental hazards or biological hazards class in IATA DGR, and the miscellaneous category is the place for items that don’t clearly fit the other classes.

So the option that lists the nine classes exactly as described aligns with IATA DGR, while the other options introduce incorrect numbers or misplace categories like treating organic peroxides separately, or adding environmental/biological hazard classes.