These chemicals are incredibly stable and safe to breathe near the ground. They do not catch fire easily, making them perfect for household products. For many decades, companies pumped them into air conditioners and hairspray cans.
The problem begins when these gas molecules float high into the stratosphere. Up there, harsh ultraviolet light from the sun hits the stable molecules. This intense energy snaps the bond between the carbon and chlorine atoms.
Breaking this bond releases a highly reactive chlorine atom called a radical. This free chlorine radical immediately attacks a nearby protective ozone molecule. The chlorine steals an oxygen atom and destroys the protective ozone shield.
Worse, the chemical reaction quickly frees the same chlorine atom again. That single chlorine radical can destroy thousands of ozone molecules over time. This repeating cycle caused the massive hole in the Antarctic ozone layer.
Global leaders finally signed the Montreal Protocol in 1987 to stop this. They agreed to stop making these chemicals to let the ozone heal. Students often think these gases just trap heat to cause global warming. While they are greenhouse gases, their main threat is actually destroying ozone.