Write the unit 'used for measuring ozone thicknes

Explanation

### Step-by-Step Solution

1. **Understanding Ozone**: Ozone is a gas composed of three oxygen atoms (O3) and is found in the stratosphere, which is a layer of the Earth's atmosphere.

2. **Function of Ozone Layer**: The ozone layer acts as a protective shield that absorbs and blocks the majority of the sun's harmful ultraviolet (UV) radiation.

3. **Measurement of Ozone Thickness**: The thickness of the ozone layer is measured to understand its concentration in the atmosphere.

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