Dangerous goods are articles or substances which are capable of posing a significant risk to health, safety or property when transported by air. The International Air Transport Association (IATA) categorizes dangerous goods into nine classes:

• Class 1 - Explosives
• Class 2 - Gas
• Class 3 - Flammable liquids
• Class 4 - Flammable solids
• Class 5 - Oxidizing substances and organic peroxides
• Class 6 - Poisonous (toxic) and infectious substances
• Class 7 - Radioactive materials
• Class 8 - Corrosives
• Class 9 - Miscellaneous articles and substances: asbestos; dry ice; environmentally hazardous substances; life-saving devices; machines incorporating internal combustion engines; magnetized material; polymeric beads; self-propelled vehicles; zinc dithionite; any liquid or solid which has anaesthetic, noxious or other similar properties which could cause extreme annoyance or discomfort to passengers and/or flight crew members