Ozone is a gas composed of three oxygen atoms, represented chemically as O3. It occurs naturally in the Earth's atmosphere, primarily in the stratosphere, where it forms the ozone layer. This layer plays a crucial role in protecting life on Earth by absorbing the majority of the sun's harmful ultraviolet (UV) radiation. While ozone is beneficial in the stratosphere, it can be harmful at ground level, where it is a major component of smog. Ground-level ozone is created by chemical reactions between sunlight and pollutants from vehicles, industrial facilities, and other sources. High concentrations can lead to respiratory problems and other health issues.