What type of device is acceptable for delivering emergency oxygen to a breathing individual?

A non-rebreather mask or a simple face mask is an effective device for delivering emergency oxygen to a breathing individual because it can provide a high concentration of oxygen. The non-rebreather mask has a one-way valve that prevents exhaled air from entering the oxygen reservoir bag, allowing the individual to inhale nearly pure oxygen. This is particularly beneficial in situations where a person may be experiencing respiratory distress and needs a significant amount of oxygen quickly.

Using a simple face mask can also provide supplemental oxygen and is useful for individuals who are breathing adequately but may require additional oxygen to maintain effective saturation levels. Both types of masks can effectively manage the patient's airway and ensure that the oxygen being delivered is maximized.

Other devices mentioned are less appropriate for this scenario. For instance, while a bag valve mask can be effective for providing positive pressure ventilation, it is typically used when the person is not breathing adequately. A nasal cannula delivers lower concentrations of oxygen and is generally suited for patients who are stable and require only minimal supplemental oxygen. An oxygen cylinder without a mask would not effectively deliver oxygen to the individual as it lacks the necessary attachment for proper administration.