Originally Posted by kellysails
When you free ascend you take in air at sea level so it would be impossible to cause issues like you would see with tank or hookah diving.
I'm not being picky, but this statement is technically wrong and dangerous. A free ascent is defined as: "An emergency procedure used to return to the surface. The diver swims or floats to the surface while breathing all the way up." If you hold your breath at any time during a free ascent you are placing yourself in harms way. The balloon example is a good one and if nothing else highlights why no one should use compressed air diving equipment without proper instruction in it's use. Which I think was the point of this post, but unfortunately the wrong term was used.
Free diving is when you take your breath at the surface, hold it, and dive to depth, then return to the surface still holding your breath. In this scenario, there is no danger of an embolism since compressed gases were not introduced into the lungs.
I think we can all now agree that diving in the absence of proper training is a very dangerous thing to do. I think we can also agree that building ones own diving rig is not small undertaking and care must be taken to use equipment and materials that are up to the intended task. Beyond that, I also think we are, at this point, beating a dead horse.