Environmental Pollution

The topic under consideration is the measurement of ozone layer thickness using Dobson units. Let's break down the question and examine the options one by one to identify the correct answer.

Explanation

Dobson units are a measure of the concentration of ozone in a column of the Earth's atmosphere. To understand this, we need to comprehend the role and unit of measurement for ozone.

Ozone Layer

• The ozone layer is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O₃) in comparison to other parts of the atmosphere.
• The thickness of the ozone layer is crucial as it helps in protecting the Earth from the harmful effects of UV radiation.

Dobson Units

• A Dobson Unit (DU) is a unit of measurement that describes the total amount of ozone in a column of air stretching from the Earth's surface to the edge of space.
• 1 Dobson Unit is equivalent to a layer of ozone that would be 0.01 millimeters thick under standard temperature and pressure at the Earth's surface.

Analysis of Options

1. CFCs: Chlorofluorocarbons (CFCs) are chemicals that contribute to ozone depletion, but they are not measured in Dobson units.
2. Stratosphere: The stratosphere is a layer of the Earth's atmosphere, not specifically measured in Dobson units.
3. Ozone: This is the correct answer. Dobson units are specifically designed to measure the thickness of the ozone layer.
4. Troposphere: This is the lowest layer of Earth's atmosphere, not measured in Dobson units.

Conclusion

Based on the above analysis, the correct option is Ozone as Dobson units are specifically used to quantify ozone layer thickness in the atmosphere.