What commonly causes sinus pressure as reported during flights?

Sinus pressure during flights is primarily associated with changes in atmospheric pressure. As an airplane ascends or descends, the cabin pressure changes, which can create a pressure imbalance between the sinuses and the surrounding atmosphere. The sinuses are air-filled cavities that need to equalize with external pressure; a rapid change in altitude does not allow sufficient time for this adjustment, leading to discomfort or pain.

When the external pressure decreases during ascent, the air inside the sinuses expands and can create a sensation of fullness or pressure. Conversely, during descent, the pressure outside increases, which can exacerbate feelings of blockage if the sinus passages are congested or if there is an inability to equalize pressure properly.

In contrast, factors like changes in temperature, humidity, and air quality may impact overall comfort or respiratory function but do not directly cause the specific pressure-related issues experienced by passengers in relation to their sinuses during flight. Therefore, atmospheric pressure changes are the direct cause of sinus pressure while flying.