Hazardous Materials (HAZMAT) are bad.
Keeping them off our airplane is good.
Items that are considered Hazardous Materials (HAZMAT) are prohibited on board aircraft. Many of these items seem harmless on the ground but when transported by air can be dangerous. Some common household items that are considered Hazardous Materials are listed below:
You are responsible to inform the pilot of any hazmat you may be carrying on your person or in you baggage before boarding. If you're not sure if an item you're carrying is considered Hazardous Materials, please ask your pilot or call us at 305-234-8800.
Vibrations, static electricity, and temperature and pressure variations can cause items to leak, generate toxic fumes, start a fire, or even explode. Hazardous materials include, but are not limited to: Explosives, Gases, Flammable Liquids and Solids, Oxidizers, Toxic and Infectious Materials, Radioactive Materials, Corrosives and many other items that can endanger the traveling public when not handled correctly. The good news is that many of the hazardous materials we can't live without are allowed in our baggage, but only if we follow the rules.
-- FAA Hazmat Safety Website