Well, I'll weigh in on this one... It appears that, as I read it, no one who has responded has any practical experience using an Ozonics unit, but all have an opinion. I can tell you why I bought one, and what my experience has been after using it all of last season. After that, what you decide will be up to you.
Two years ago, I was guiding in Missouri when I first encountered a hunter who had one. He was begging us to put him in stands where we thought the wind would kill his chances, in spite of the fact that he had an Iowa tag that took four years to get. We had no one else who would be hunting that farm after he left, so the decision was made to let him have his way.
Each evening he was telling us about all of the deer that had passed directly downwind without spooking, and showing us pictures he had taken of the bucks he passed. These were three and four year old deer, not yearlings, and many of the pics showed deer with their noses in the air, but not alarmed...
Since I had an Iowa tag for last season, I decided that I could make the unit fit my budget, and that I would hunt no matter which way the wind was blowing in the same spot. The possibility that I might encounter some of the same deer was looming in my mind, and I was determined that some of them would be plenty good enough for me to punch that tag. I thought that if they encountered the ozone the second time it would be interesting to see how they reacted.
I climbed into the stand each day, hung the unit, and watched deer after deer go directly through my scent stream. Some paid no attention at all, while others would stop, raise their noses, and then just ease off, showing no sign of alarm.
Now, bear in mind that the leaves were falling, and I could see them blowing straight from overhead to the deer. So, there were no funny currents to "save" me...
There were also at least six other hunters in camp who were using Ozonics, and experiencing the same results.
I am not sponsored by Ozonics, nor do I have any financial incentive to promote this product. I know folks in the hunting industry who are not sponsored, and who are also using one, and that speaks volumes to me, because it is definitely one more piece of gear to carry along.
I believe that no matter what the level of ozone being emitted, it is very effective at fooling deer, at least to the point where they just don't spook. And, that is all I can ask for it to do.
As for inhaling the ozone: The bracket hold the unit away from the tree, and the fan blows it even further out. If you have any appreciable wind, the ozone "curtain" doesn't fall in your face, so you will not be inhaling it. If you do, and it can happen, you will know it immediately. And, I would strongly advise that you adjust things, or turn the machine off, if you cannot avoid inhaling it. In my experience, I get the urge to cough with even the slightest amount of smelling it.
Do what you wish, but I am not getting in a tree without it!