What depth is helium recommended for diving to prevent nitrogen narcosis?

Helium is recommended for diving at depths above 150 feet of seawater (fsw) to help prevent nitrogen narcosis, which can occur under high-pressure conditions due to the increased nitrogen levels being breathed. As divers go deeper, the partial pressure of nitrogen increases, leading to potential impairment and narcosis.

Using helium as a gas mix in deeper dives allows for a reduction in the amount of nitrogen being breathed, thus lowering the risk of narcosis. Helium does not contribute to narcotic effects like nitrogen does, making it a preferred choice for deep dives where nitrogen narcosis is a significant concern.

Choosing a depth above 150 fsw aligns with technical diving practices that prioritize safety by managing gas mixtures effectively, which is crucial for both performance and safety during underwater operations.