What is dry drowning and how common is it in children?

See below: Dry drowning or delayed drowning occurs when a small amount of water goes into the lungs. How it ocurrs is not completely understood but it is thought that water can cause the breathing tube to tighten (laryngospasm) or cause pulmonary swelling. It can happen up to 24 hours after the water gets into the lungs. There are no reports that say how many drownings are this type.