Which statement regarding the carriage of oxygen for medical use is TRUE?

The statement that only approved portable oxygen concentrators may be carried is true because aviation regulations and airline policies often restrict the type of medical oxygen devices passengers are allowed to bring on board. Portable oxygen concentrators are specifically designed for air travel and meet regulatory safety standards for operation on aircraft. These devices are engineered to be safe in an airborne environment, ensuring they do not pose risks during flight due to leaks or combustion issues.

In contrast, other forms of compressed gas medical oxygen, such as tanks or cylinders, may not be allowed due to safety concerns, including the potential for pressure hazards and the risk of fire. Additionally, while oxygen can be essential for medical purposes, regulations about its storage and usage are strictly enforced to maintain safety within the cabin during flight. Therefore, passengers requiring medical oxygen must adhere to the specific guidelines provided by airlines, which typically favor portable concentrators approved for air travel.