That "high concentration" decision is part of the problem. I live in a city where the eastern boundary is a Great Lake. Levels of O3 are higher, at this point I can't quote a source other than a local news station, are higher in the vicinity of bodies of water. The level of concentration is not "in" the water, but in the immediate vicinity of the water. Most all of the recording stations are in such locations. But to presume that such readings have any bearing within the city confines five miles away can not be supported. Heck the ambient temperature does not remain constant over that distance!

Quote Originally Posted by Thorne View Post
I can't find any information regarding the natural concentration of ozone in water. In fact, unless the water is pure, the ozone would quickly react with any contaminants, destroying the ozone.

And ozone (O3) IS a pollutant at low levels. It can cause headaches, burning in the eyes, and respiratory irritation. People with resperatory problems already are particularly affected. So monitoring those levels is very important. And I would expect the monitoring to occur in those areas which are most likely to have high concentrations.