Humidity is the concentration of water vapor in the air. This is an important and often overlooked variable in maintaining good health. During the winter months, cold temperatures and furnaces lead to dryer air with low humidity.
High and low humidity extremes can trigger nasal congestion or the perception of congestion. Dry air with low humidity can increase feelings of being congested as your sinus membranes dry out and become irritated. The authors of one study found high humidity contributed to nasal patency, or the experience of breathing through clear nostrils.