The Transportation Security Administration (TSA) has strict guidelines regarding items that are prohibited on flights. These rules are in place to ensure the safety of passengers and crew by preventing potential hazards in both carry-on and checked luggage.
Flammable substances, whether gases, liquids, gels, or solids, are banned due to the risk of fire. The danger they pose is significant as a fire onboard can quickly become uncontrollable. Pressurized containers and explosive materials like medical oxygen canisters also require inspection because they could compromise an aircraft's integrity if there is a sudden release of pressure.
Firearms and ammunition are only allowed as checked baggage after inspection. This measure is taken to prevent any threats from firearms during a flight. Poisonous or reactive substances, such as strong chemicals like bear spray, are generally not permitted even if sealed. The safety of the flight depends heavily on maintaining clean cabin air.