Usage of _________ in refrigeration system leads to the ozone layer depletion.

Explanation

### Step-by-Step Solution:

1. **Identify the Context**: The question is about substances used in refrigeration systems that contribute to ozone layer depletion.

2. **Recognize the Substance**: The specific substance that is commonly associated with refrigeration and is known to deplete the ozone layer is CFC, which stands for Chlorofluorocarbons.

3. **Explain the Mechanism**: CFCs are released into the atmosphere through various means, including aerosols and refrigeration systems. Once in the atmosphere, they undergo breakdown due to ultraviolet (UV) radiation from the sun.

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