Yes..actual studies...
I have observed (with joy) "flying" fish in Subic Bay, Philippines, they are out of the water for a 10-20 seconds or so...
I have observed large mouth bass jumping from the water to catch a bug...
I have fly fished...enticing the steelhead of washington state to strike on or above the surface of beautiful cobble stone rivers...
I have observed my own fish, fresh and salt alike, strike the surface for floating food, then go down and blow bubbles...
My feelings are...with this vast variety of marine and freshwater life intaking air as natural as they swim...how can it be harmful to them? I do not believe so...
That is what I base my statements on...