Chlorofluorocarbons (CFCs) are industrial chemicals that release chlorine atoms when exposed to ultraviolet radiation in the stratosphere, causing depletion of the protective ozone layer. The ozone layer, located 9 to 18 miles above Earth’s surface, absorbs approximately 97 percent of harmful ultraviolet B radiation. CFC emissions from refrigerants, propellants, and solvents threatened this critical atmospheric shield.
Chemical Mechanism
When CFC molecules reach the stratosphere, UV radiation breaks the chemical bonds, releasing reactive chlorine. Each chlorine atom catalytically destroys approximately 100,000 ozone molecules before becoming inert. A single chlorine atom remains active for 50 to 100 years, creating long-term atmospheric damage even after CFC emissions cease.
Health and Environmental Impact
Ozone depletion increases ground-level ultraviolet B exposure, causing skin cancer, cataracts, and immune system suppression in humans. UV radiation damages crops, marine ecosystems, and phytoplankton that form the ocean food chain. The Antarctic ozone hole, discovered in 1985, covered approximately 9 million square miles at its peak, prompting urgent international action through the Montreal Protocol.