What is meant by ozone shield ? How the CFC's and ozone depleting substances affect Ozone shield ?

Explanation

### Step-by-Step Text Solution

**Step 1: Definition of Ozone Shield**
The ozone shield refers to the ozone layer, which is a region of Earth's stratosphere that contains a high concentration of ozone (O3) molecules. This layer is located approximately 20 to 26 kilometers above sea level and acts as a protective barrier, absorbing the majority of the sun's harmful ultraviolet (UV) radiation.

**Step 2: Importance of the Ozone Shield**
The ozone shield is crucial for maintaining a viable environment for life on Earth. By filtering out harmful UV rays, it helps prevent various health issues, including skin cancer and cataracts, and protects ecosystems.

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