Human: I've heard that the ozone layer is being depleted. What is causing this? Assistant: 
The ozone layer is a layer of gas in the atmosphere that absorbs ultraviolet radiation from the sun. This helps protect life on Earth from harmful UV radiation. In recent years, scientists have observed a decrease in the amount of ozone in the stratosphere, which is the part of the atmosphere where the ozone layer is located. This decrease has been linked to human activities such as the release of certain chemicals into the atmosphere and the use of certain types of air conditioning and refrigeration systems.