The risk of embolus comes from gases entering in to the bloodstream. Pressure is the biggest factor. Many ozone units are designed with such a high concentration output that the oxygen flow rate has to be really upped to get the ozone concentration down to safe limits
Where did you get this info. I slept in a room with a industrial ozonator, that carried a severe warning against being anywhere near it when it is running. Kept the door shut as well, and here I am typing away. I had no bad side effects, other than a heavy duty herz. Did get rid of a bunch the stuff that is trying to kill me. A blood test a week or so after, showed no free radicals in my blood.
The odds of dying from the mds mistakes are way higher.
I've done every ozone insufflation, several times with my ozone generator from Nature-Kleen, am only the better for it. If ozone was killing people I doubt you would be able to buy as easy as you can.