Ozone hole is

Options

A. Partial gap in stratospheric ozone layer over Antarctica
B. Partial gap in stratospheric ozone layer over Arctic pole
C. Thinning of ozone layer over polar regions
D. Excessive buildup of lower troposphere ozone

Answer

### Step-by-Step Solution:

1. **Definition of Ozone Hole**: The ozone hole refers to a significant thinning of the ozone layer, primarily observed over polar regions, particularly Antarctica.

2. **Cause of Ozone Hole**: The thinning of the ozone layer is caused by the release of chemical compounds, particularly those containing chlorine and bromine. These compounds are often released through industrial activities and other human actions.

3. **Impact on Polar Regions**: The phenomenon mainly affects the polar regions, with Antarctica being the most severely impacted area. The ozone hole over Antarctica is the largest and has not yet closed.

4. **Recent Developments**: The ozone hole over the Arctic, in contrast, has shown signs of recovery and closed in 2020, indicating some positive effects of international efforts to reduce ozone-depleting substances.

5. **Misconceptions**: It is important to note that excessive buildup of ozone in the lower troposphere does not contribute to the ozone hole. Instead, it leads to smog formation, which has harmful effects on human health, such as triggering asthma and causing lung damage.

### Final Answer:
The ozone hole is the thinning of the ozone layer over the polar regions, primarily caused by human-released chemical compounds containing chlorine and bromine.

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