What defines exceptional exposure for a dive?

Exceptional exposure for a dive is defined by specific criteria that indicate increased risk and requirements for careful planning, training, and safety protocols. Among the options provided, any air dive deeper than 190 feet of seawater (fsw) represents a significant threshold.

Diving deeper than this limit introduces a range of physiological challenges due to increased pressure effects on the body, particularly regarding nitrogen absorption and the risk of decompression sickness. At these depths, divers are subject to more stringent regulations and guidelines related to dive planning, including the need for additional safety measures during ascent and potentially using specific diving gas mixtures to manage the risk of narcotic effects and oxygen toxicity.

In contrast, other scenarios such as diving deeper than 100 fsw or having a dive with a decompression time over 30 minutes may increase risk but do not specifically categorize a dive as "exceptional" under standard guidelines. Similarly, an oxygen dive longer than 60 minutes, while certainly significant, typically pertains to specific oxygen management protocols rather than defining exceptional exposure in the broader context of diving depth limits. Therefore, the designation of exceptional exposure is appropriately aligned with the depth specified in the correct choice, highlighting the heightened danger and complexity associated with such dives.