Which measure uses gas mixes to limit nitrogen effects?

• A. Avoid all dives
• B. Always dive to max depth
• C. Use gas mixes to limit nitrogen effects
• D. Ignore early signs

Answer: (C)

Adjusting the breathing gas composition is a direct way to manage nitrogen-related effects in diving. By using gas mixes that lower the nitrogen fraction or replace nitrogen with helium, divers reduce the partial pressure of nitrogen at depth, which lowers the risk of nitrogen narcosis and reduces decompression stress. Nitrox blends increase oxygen content and decrease nitrogen, extending safe bottom time at recreational depths, while deeper dives use trimix (oxygen, helium, and nitrogen) to further lessen nitrogen narcosis and shorten decompression requirements because helium is less narcotic. This approach specifically targets nitrogen load and narcosis, making it the appropriate measure. Other options don’t employ gas mixing to control nitrogen effects and instead either avoid diving, push depth beyond safe limits, or ignore early warning signs.