What Is the Ozone Layer?
The ozone layer is a region of Earth's stratosphere, approximately 15 to 35 kilometers above the surface, where ozone (O3) molecules are concentrated at higher levels than in other atmospheric layers. It acts as a shield by absorbing most of the Sun's harmful ultraviolet (UV) radiation, particularly UVB rays, which can damage living organisms.
Key Causes of Ozone Depletion
Ozone depletion primarily results from human-made chemicals, such as chlorofluorocarbons (CFCs), halons, and hydrochlorofluorocarbons (HCFCs), released from refrigerants, aerosols, and industrial processes. These substances rise to the stratosphere, where ultraviolet light breaks them down, releasing chlorine or bromine atoms that catalytically destroy ozone molecules through chain reactions.
Practical Example: The Role of CFCs
In the 1980s, widespread use of CFCs in spray cans and air conditioners contributed to the Antarctic ozone hole, where seasonal depletion led to a 60% reduction in ozone levels over the South Pole. This example illustrates how a single class of chemicals can trigger widespread atmospheric damage, as one chlorine atom can destroy thousands of ozone molecules before being neutralized.
Importance and Real-World Applications
The ozone layer is crucial for preventing UV radiation from reaching Earth's surface, which helps avoid increased rates of skin cancer, cataracts, and ecosystem disruptions in marine life. Its depletion has prompted international efforts like the 1987 Montreal Protocol, which phased out ozone-depleting substances, demonstrating how global policy can mitigate environmental threats and aid atmospheric recovery.