What can lead to an increase in carbon dioxide buildup in divers?

Inadequate ventilation and overexertion can significantly contribute to an increase in carbon dioxide (CO2) buildup in divers. When divers exert themselves physically while underwater, their body's demand for oxygen increases, resulting in increased production of CO2 as a byproduct of metabolism. If ventilation is inadequate, meaning the diver is not able to effectively exchange gases, this leads to a reduction in the exhalation of CO2. The combination of high physical activity and poor gas exchange can quickly elevate the levels of carbon dioxide in the bloodstream, leading to conditions like hypercapnia, which can impair cognitive and physical performance and create dangerous situations underwater.

In contrast, excessive hydration does not directly influence carbon dioxide levels, while deep diving without proper training pertains more to safety and risk management rather than CO2 buildup. Improper breathing technique can have an effect on overall diving efficiency and gas exchange but is specifically tied to how divers breathe rather than the general interaction of exertion and gas exchange.