What physical condition can put a diver at risk for barotrauma?

Sinus congestion or allergies can create significant risks for a diver due to their impact on the sinuses and the Eustachian tubes, which are critical for equalizing pressure during descent and ascent underwater. When a diver experiences sinus congestion or has allergic reactions that lead to swelling of the nasal passages, it can obstruct normal airflow and pressure equalization. This inability to equalize pressure can result in barotrauma, which is damage to body tissues caused by unequal pressure, particularly affecting the sinuses and middle ear.

During a dive, as a diver descends and the surrounding water pressure increases, the air in the sinuses and middle ear must also equalize to prevent damage. If the Eustachian tube is blocked due to congestion or allergies, pressure cannot equalize properly, leading to possible rupture of the eardrum or sinus cavities, or other painful complications. Therefore, individuals with these conditions need to be especially cautious and may need to avoid diving until they have recovered.

Other conditions listed may have implications for diving safety, but they do not directly lead to barotrauma through the mechanism of pressure equalization challenges in the same way that sinus congestion does.