Ozone enters leaves through small pores on the leaf surface and causes damage to leaf cells. As ozone pollution does not result in a residue on the leaves, visible leaf injury is the most easily detectable evidence of damage.
Ozone damage can cause spotting on the leaf surface, for example in a) soybean (Glycine max), b) courgette (Cucurbita pepo).
Find out more information on the symptoms of visible ozone injury.
There are also other possible causes of leaf damage that may be mistaken for ozone injury, including leaf viruses and disease.
We have created a gallery of photographs of examples of ozone injury in a variety of different species: