Final answer:
The stratosphere contains the most ozone in the Earth's atmosphere. This layer is crucial for absorbing harmful UV radiation from the sun and protecting life on Earth. International efforts have reduced ozone depletion by phasing out harmful CFCs.
Step-by-step explanation:
The Earth's atmosphere is composed of several layers, but when considering there are four distinct layers in the atmosphere, the discussion usually focuses on the troposphere, stratosphere, mesosphere, and thermosphere. The layer that contains ozone the most is the stratosphere. The ozone layer is located in the lower portion of the stratosphere, from approximately 9 to 18 miles above the Earth's surface, where it plays a critical role in absorbing potentially harmful ultraviolet (UV) radiation from the sun.
Near the top of the stratosphere, ozone molecules (O3) protect all life on Earth by absorbing the majority of the sun's dangerous ultraviolet radiation. This has been crucial for enabling life to thrive on our planet. However, in the 1980s, scientists detected a thinning of the ozone layer, known as the 'ozone hole', attributed mostly to human-produced chemicals such as chlorofluorocarbons (CFCs). Due to international action and the phasing out of CFCs, the depletion has halted, and the ozone layer is gradually recovering.