When is a material only regulated during transportation?

A material is regulated during transportation primarily in accordance with specific modes of transport and the conditions under which it is handled. The choice stating that a material is only regulated when offered or transported by aircraft highlights the fact that certain materials, particularly those classified as hazardous, fall under rigorous regulations established by various authorities, including the International Air Transport Association (IATA) and the Federal Aviation Administration (FAA).

Air transport typically has more stringent requirements due to factors such as altitude, pressure changes, and the potential hazards posed by materials in the confined spaces of an aircraft. Therefore, even if a hazardous material is not regulated in other contexts or modes (like rail, road, or international shipments), it must comply with specific regulations when being offered or transported by aircraft. This adherence ensures safety for the aircraft, personnel, and passengers, as well as compliance with international standards governing hazardous materials.