PADI Divemaster Certification Practice Exam

What can result from expanding air during ascent if a diver holds their breath?

1. Lung overexpansion injuries

2. Normal lung expansion

3. Improved oxygen absorption

4. Increased blood circulation

The correct answer is: Lung overexpansion injuries

Expanding air during ascent can lead to lung overexpansion injuries, which occur when a diver holds their breath while ascending. As a diver ascends, the pressure surrounding them decreases, and the air trapped in the lungs expands. If a diver is holding their breath, this expanded air has no path to escape, which can cause the lung tissues to stretch beyond their normal capacity. This overstretching can result in rupture or tearing of the lung tissue, leading to serious conditions such as pneumothorax (collapsed lung) or arterial gas embolism, which can be life-threatening. The other responses, while related to dive physiology, do not accurately describe the consequences of holding one's breath during ascent. Normal lung expansion is part of healthy breathing processes, but when holding one's breath under changing pressure, this can lead to severe consequences instead. Improved oxygen absorption may occur during normal breathing or proper ascent, but it is irrelevant when considering the risks of breath-holding. Increased blood circulation is a natural physiological response to many activities but does not directly connect to the risks associated with expanding air in a diver's lungs during ascent.