Nothing appears to be wrong with your plants, but the leaves age and drop off weeks before their time. This could be a real problem for farmers if potato leaves are dying, for instance, while tubers are supposed to be growing. Similarly, if crops like beans lose their leaves before the time when they move nitrogen from their leaves to their seeds, the pods may not fill. It's hard to point the finger directly at ozone when you're out in the world, though, because ozone is never found apart from other stresses. Bright, hot conditions that can harm plants are conducive to ozone production.
Ozone also interacts heavily with insects and pathogens.
It's difficult to just walk out into the woods and identify ozone damage. It's very complex. Biologists like complexity that's life. Researchers have studied the interactions between soil fertility and ozone damage since the 1960s. But they found that different species responded in various ways to the range of fertility treatments.