The ozone that is said to pollute the nature is in fact NOX pollution and not ozone. It is a fact that NOX disturb the measuring of ozone! The best way to explain this is: Ozone smells much more strongly and characteristic. With a content of 0,02 ppm you can smell the ozone (in a working room the allowed content is 0,1 ppm which is unpleasantly high). If you have a content of ozone that high in the nature, which you sometimes hear about in the news, it would smell heavily outside.