Environmental Protection Agency (EPA) MVAC Certification

Which layer of the Earth's atmosphere is the ozone layer primarily found?

1. Troposphere

2. Stratosphere

3. Mesosphere

4. Thermosphere

The correct answer is: Stratosphere

The ozone layer is primarily found in the stratosphere, which is the second layer of Earth's atmosphere, located above the troposphere and below the mesosphere. This layer is crucial for life on Earth because it contains a high concentration of ozone (O3) molecules. Ozone plays a vital role in absorbing the majority of the sun's harmful ultraviolet (UV) radiation, thereby protecting living organisms from its damaging effects, which can include skin cancer and cataracts in humans, as well as negative impacts on wildlife and ecosystems. The stratosphere's relative stability, along with the presence of ozone, allows it to efficiently absorb UV radiation, making it a unique and essential part of the atmospheric system. The troposphere, which is closest to the Earth's surface, contains most of the atmosphere's weather and is not the correct location of the ozone layer. The mesosphere and thermosphere lie above the stratosphere and do not have the same concentration of ozone. Thus, the correct answer is the stratosphere, where the ozone layer is predominantly located.