G., I googled your question because I have a two year old also and I had never heard of that possibility before. He too has tumbled into the baby pool before. The two articles I came across both discussed near-drowning incidents with toddlers, but I don't think your son's situation fit the definition of near drowning. What I learned in my son's toddler water readiness class w/parks and rec, which was repeated in the articles I found regarding drowning, is that upon an unexpected submersion, the baby automatically holds his breath. He will continue to do so until he can't anymore, that's when they are in danger of inhaling water. It sounds to me like you rescued him quickly enough that he did not aspirate. Also, a few of the times I submerged Owen in swim class, he was not expecting it and gasped, choked and sputtered a bit afterwards, but was essentially fine. If your son was not forcefully exhaling water or gasping for air, I think you caught him in time and he will be fine. Hopefully you'll get a response from a nurse though because I'm curious about this issue too.