Which causes regional pollution

Options

A. Smog
B. Acid rain
C. `O_(3)` layer depletion
D. both A and B

Answer

### Step-by-Step Solution:

1. **Understanding Regional Pollution**:
- Regional pollution refers to pollution that affects a specific area or region rather than being widespread globally. It is often caused by localized sources of pollution.

2. **Identifying Options**:
- The options given are:
- A) Smoke
- B) Acid Rain
- C) Ozone Layer Depletion
- D) Both A and B

3. **Analyzing Smoke**:
- Smoke is a mixture of smoke and fog, containing pollutants like ground-level ozone, carbon monoxide, nitrous oxides, and volatile organic compounds.
- These pollutants are primarily released from vehicular emissions and industrial activities, especially in metropolitan areas.
- Therefore, smoke contributes to regional pollution.

4. **Analyzing Acid Rain**:
- Acid rain occurs when sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) react with water and oxygen in the atmosphere.
- This reaction forms sulfuric acid and nitric acid, leading to acidic precipitation that can harm ecosystems and structures.
- Acid rain is also a significant contributor to regional pollution.

5. **Evaluating Ozone Layer Depletion**:
- Ozone layer depletion refers to the thinning of the ozone layer in the Earth's stratosphere, primarily caused by chlorofluorocarbons (CFCs) and other ozone-depleting substances.
- While it is a form of pollution, it does not contribute to regional pollution as it has global implications.

6. **Conclusion**:
- Since both smoke and acid rain are contributors to regional pollution, the correct answer is option D) Both A and B.

### Final Answer:
**Both A and B (Smoke and Acid Rain) cause regional pollution.**

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