Chemically, ozone is oxygen (O2) with an extra molecule added (O3). Electrically, ozone is oxygen with a higher energy level, making it unstable and highly reactive.
Oxygen moves and changes in a cycle, just as there is a cycle of water. Oxygen is released during photosynthesis by land plants (such as shrubs, flowers and trees) and ocean phytoplankton (mostly unicellular diatoms), which rises up in the atmosphere, about 25-30 miles. At this atmospheric level the oxygen is energized by a part of the ultraviolet spectrum of energy from the sun, and this leads to ozone production. Because Ozone is heavier than air it begins to descend. Ozone immediately attaches itself to airborne particles if it contacts them, oxidizing them, and thus cleaning the air. If it encounters water vapor, Ozone can attach itself to it, forming hydrogen peroxide. Through natural processes, both rain and snow contain hydrogen peroxide. This is why plants grow better from rainwater than from irrigation as it contains the added hydrogen peroxide element and benefits the plant.
At ground level, ozone attaches itself to all pollutants, oxidizing them and cleaning the air, Ozone has incorrectly been blamed for contributing to smog levels. Ozone is present in smog only transiently at around 25 parts per hundred million.
The ozone that exists in the atmosphere is produced by nature and it is attracted to pollutants because of opposite charge - it attempts to oxidize them and clean the air. The problem lies in there being too little ozone to complete the job and counteract smog, not too much.
Ozone is also created near the ground by lightning. The fresh smell in the air after a thunderstorm is ozone that has formed during the element interaction.