The preferred oxygen delivery device to use when providing emergency oxygen to a non-breathing person is a:

When providing emergency oxygen to a non-breathing person, the preferred device is a bag valve mask. This device is designed to deliver positive pressure ventilation to someone who is not breathing effectively. It creates a seal over the patient's mouth and nose, allowing for the delivery of a higher concentration of oxygen directly into the lungs. This is crucial in emergencies where the oxygen level in the blood is dangerously low due to inadequate or absent breathing.

The bag valve mask is highly effective because it can deliver 100% oxygen when attached to an oxygen source, and it allows a trained rescuer to effectively ventilate the patient using rhythmic squeezes of the bag, delivering air or oxygen consistently, which is vital for survival until further medical assistance can be provided. Other devices, like a nasal cannula or simple face mask, are not suitable in this scenario because they do not provide the same level of ventilation support required for a non-breathing individual.