Is claustrophobia due to fear of air stopped circulating?

Enclosed Spaces: Claustrophobia is an abnormal tendency to feel terror in small spaces. It is often classified as an anxiety disorder and can result in panic attacks. It can occur in a wide variety of settings such as a crowded elevator, a room without windows, and even with tight-necked clothing. One study estimates that a 5-7% of the world population is affected by severe claustrophobia. There is treatment.

Fear: It's actually a fear of closed in spaces with no way of escaping. For some the fear can be so debilitating it seems to the person that the walls of the closed in space are actually closing/squeezing in further.