I don't believe that UV lamp can produce enough O3 to hurt you. Ozone will dissipate pretty fast. If you run more air thru the UV lamp it produces less ozone and not enough air and you can't saturate the water enough to allow the O3 to work properly. The amount of ozone you produce will be determined by the flowrate of your pump and the amount of oxygen being introduced to the system. Ozone is great for killing organics, but expensive to maintain. Some people claim that it smells like the air after a thunderstorm. I think it smells more like very sweet watermelon. High levels will cause some people to feel sick to their stomach, headache, maybe a scratchy throat. As long as you don't take the output and breathe it straight in you should be fine. I breathed some real high levels of ozone and i'm fine. (Unless you ask my wife.) It was sickly sweet smell at those levels.

It's great for removing odors, though. That's the only reason i want an ozone generator.