1. Stratospheric Ozone:

* Photochemical reactions: This is the primary way ozone is formed in the stratosphere. It involves the following steps:

* Ultraviolet (UV) radiation from the sun splits oxygen molecules (O2) into single oxygen atoms (O).

* These oxygen atoms then react with other oxygen molecules to form ozone (O3).

2. Tropospheric Ozone:

* Photochemical smog: This is the primary way ozone is formed in the troposphere (the lower part of the atmosphere). It's a complex process involving:

* Nitrogen oxides (NOx) and volatile organic compounds (VOCs) are emitted from sources like cars, factories, and power plants.

* In the presence of sunlight, these pollutants react with oxygen to form ozone.

In summary: Ozone is produced both naturally and through human activity, but the process differs depending on its location in the atmosphere.