Human: Why is there a hole in the ozone? Assistant: 
The hole in the ozone layer is caused by chlorine and bromine compounds that are released into the atmosphere from man-made chemicals, such as chlorofluorocarbons (CFCs). These chemicals were used for decades in aerosol cans, refrigerators, air conditioners, and other products. When they were released into the atmosphere, they reacted with oxygen and broke down into smaller molecules called free radicals. These free radicals then attacked the ozone molecules, breaking them apart and creating holes in the ozone layer.