Most scuba agencies recommend to not dive deeper than 40 meters to manage the risks of Nitrogen Narcosis. This was not always the case, in older tables; the maximum depth was 60 meter, the depth of 40 meters was mostly determined to minimize the risk of Oxygen toxicity, while Nitrogen Narcosis was considered something you had to learn to deal with, like a drunk man trying to walk in a straight line.
Nitrogen Narcosis itself is not biologically unhealthy, it does not damage the body. Most divers will resurface feeling completely normal. However, if you come up and are still feeling a mild buzz, do not worry, this is not uncommon and it will dissipate during your surface interval time.
When you are in a state of narcosis it will affect your mood, thoughts and decision-making. A single bad judgement call, such as choosing to linger at depth because it feels good, can be fatal.
After descending below 40 meters you must pay extra careful attention to your condition and the condition of those who are diving with you. Some divers are not even aware that they are in a state of narcosis, so as a dive buddy you must constantly monitor your partner's condition. Some divers will be very aware of their narcosis and must make their own judgement call as whether they wish to continue.
During this training we plan a dive between 38 and 60 meter to learn recognize and manage the symptoms, allowing you to handle the effects more effectively.
Prerequisites
- You are a certified Freediver
- You are a certified Scuba Rescue Diver
- You have undergone the FCOA Panicked proofing
- You are a certified Nitrox Diver
- You have completed a independent diver program
- You are trained for decompression diving.
- You have completed the FCOA In Water Recompression IWR preparedness quiz.
- You have DAN's (Divers Alert Network) phone number in your contact list on your phone in the event of an emergency.
Strategies to manage Nitrogen Narcosis
- Have a simple dive plan and memorize and repeat it in your head. For example: "When I reach my NDL I will push my inflator button."
- Keep your heart-rate and breathing low and slow. The slower you move and breathe, the less Nitrogen you breathe.
- If your heart-rate and breathing are fast, then sit down on the bottom and don't move, or hang on the dive line without moving
- Once you arrive at maximum depth have a moment to actively examine how you feel. Most divers feel overly happy, more happy than normal (called euphoria.) If you are aware that you are in a state of narcosis, have a predetermined hand signal to give your dive buddy so that they are aware of your condition and can closely monitor your behavior. For FCOA scuba divers, this signal is the middle finger.
- Keep an eye on your buddy: if their behavior seems out of the ordinary give them the hand signal for ascent or take them up 10 or 15 meter to reduce the effects of nitrogen narcosis.
Exercises
- Before you go down do a reaction speed test. For example: measure 3 times how long it takes you to draw a three-dimensional house with a door, a window and chimney. Draw it every time on a blank sheet of paper so you're forced to draw it from memory and not copying it from another image.
- Once you reach your deepest point, write down on your slate your dive time.
- Take a minute sit down, slow down and write down how you feel.
- Do your reaction speed test while your buddy times you.
- At the end of your bottom time your instructor will pretend to be negatively effected by nitrogen narcosis, recognize this and bring him up 10 or 15 meters till he starts acting normal again.
