Да, на пръв поглед звучи ужасно, и все пак, като се зачетох в укипедията, нещата звучат доста правдоподобно:
http://en.wikipedia.org/wiki/OzoneOzone reacts directly with some hydrocarbons such as aldehydes and thus begins their removal from the air, but the products are themselves key components of smog. Ozone photolysis by UV light leads to production of the hydroxyl radical OH and this plays a part in the removal of hydrocarbons from the air, but is also the first step in the creation of components of smog such as peroxyacyl nitrates which can be powerful eye irritants. The atmospheric lifetime of tropospheric ozone is about 22 days; its main removal mechanisms are being deposited to the ground, the above mentioned reaction giving OH, and by reactions with OH and the peroxy radical HO2· (Stevenson et al, 2006).[16]
There is evidence of significant reduction in agricultural yields because of increased ground-level ozone and pollution which interferes with photosynthesis and stunts overall growth of some plant species.[17][18]
Certain examples of cities with elevated ozone readings are Houston, Texas, and Mexico City, Mexico. Houston has a reading of around 41 ppb, while Mexico City is far more hazardous, with a reading of about 125 ppb.
Т.е. не самия озон е директно вреден, а продуктите, получени при реакция озон и някои други газове.
Не съм спец по химия, а и тук не е подробно обясненено, но май
озона се преобразува (ОН), и оттам "peroxyacyl nitrates"
Като положително се дава помощта му да се премахват въглеводородите от въздуха.
"plays a part in the removal of hydrocarbons from the air"