Let's say you have switched to your alternate air source which happens to be a common 2nd stage regulator octopus or one of the new alternate air source systems built into the power inflator of a buoyancy compensator. If you have enough air to last, at your normal rate of breathing, 10 minutes, that same amount of air can last 12 minutes if you were using an Air Buddy.
Would that extra 2 minutes be useful? Maybe you wouldn't need it.
Maybe it would make the difference between surviving or not.
How does the Air Buddy do this?
You need to know a few facts to understand how this happens.
The Air Buddy doesn't work that way.
1. You don't suck to get air from an Air Buddy. You squeeze the mouthpiece and the Air Buddy blows the air into your mouth.
2. The air that is blown in is fresh air, with no carbon dioxide. There is no stale air in the Air Buddy itself because you never exhale into it. All the air space in an Air Buddy is fresh air. That fresh air creates a turbulence, mixing whatever stale air you have retained in your oral cavity and trachea, reducing the percentage of carbon dioxide. So the air that you are inhaling into your lungs has less carbon dioxide than what you would get from any other alternate air source system. This is the same type of system used to give breathing air to premature babies in the hospital for their well being.
3. So, each breath you take with an Air Buddy has less carbon dioxide in it, causing your body to wait for a longer period of time before your carbon dioxide level builds to a point where it triggers your breathing response.
4. The net result is that your body will automatically take only 4 breaths using an Air Buddy during the same time period it would be taking 5 breaths with any other current system.
5. This difference in breathing is controlled by your autonomic nervous system and is not even noticed by you that it is happening.
It's one more safety factor to have on your side.