At what depth may dyspnea start to become a concern for divers?

Dyspnea, or difficulty in breathing, can become a concern for divers as they descend due to increased pressure on the respiratory system. At depths below 120 feet of seawater (FSW), the combination of high environmental pressure, physiological factors, and potentially increasing gas density can lead to respiratory challenges, especially for divers who may have preexisting conditions or are not sufficiently acclimated to deeper diving.

While diving deeper than this can exacerbate the risks associated with dyspnea, the threshold of 120 FSW is significant because it marks where divers, particularly those who are not exceptionally trained or conditioned, may begin to experience noticeable breathing difficulties. As the depth increases, factors such as nitrogen narcosis, physiological stress, and increased workload on breathing become more pronounced, making it vital to recognize 120 FSW as a critical depth where these issues can manifest.

In contrast, other depths mentioned may not underscore the increased risk as distinctly as 120 FSW, making this depth a pivotal point for divers' respiratory management and preparedness.