Final answer:
For a patient with nasal passage discomfort from oxygen therapy, humidifying the oxygen is the recommended intervention to improve comfort by reducing dryness.
Step-by-step explanation:
If a patient receiving oxygen at a flow rate of 6 L/min by nasal cannula is experiencing nasal passage discomfort, the most suitable intervention would be to suggest that the patient's oxygen be humidified. This is because air is warmed and humidified in the nasal passages, which helps to ward off infection, decrease sensitivity during breathing, prevent damage to the lungs, and more. Humidified oxygen can mitigate the dryness that may be causing the patient's discomfort.