What is the effect of increasing dive duration at a constant depth?

Increasing dive duration at a constant depth leads to increased nitrogen absorption. As a diver spends more time at a particular depth, the body continues to absorb nitrogen from the breathing gas, which contains nitrogen as a significant component. This absorption occurs due to the principles of gas laws, specifically Henry's Law, which states that the amount of a gas dissolved in a liquid (in this case, blood and body tissues) is directly proportional to the partial pressure of that gas in contact with the liquid.

At greater depths, the pressure increases, which increases the density and partial pressure of nitrogen in the breathing gas. Consequently, even though the depth remains constant, prolonged exposure allows more nitrogen to dissolve into the tissues. This is why longer dive durations, all else being equal, result in more nitrogen being absorbed by the body.

Understanding this concept is crucial for divers because excessive nitrogen absorption can lead to potential risks such as decompression sickness (DCS) when ascending to shallower depths or the surface. Thus, it is essential for divers to monitor their dive time to manage nitrogen loading effectively and prioritize safe ascent practices.