Mention the major cause of air pollution in metro cities. Write any three ways by which it can be reduced.

Explanation

### Step-by-Step Solution:

1. **Identify the Major Cause of Air Pollution in Metro Cities:**
The primary cause of air pollution in metropolitan cities is the emission of harmful gases from various sources. The significant contributors include:
- Smoke stacks from thermal power plants and smelters.
- Burning of fossil fuels in industries, automobiles, and households.
- Emissions from a high volume of vehicles on the roads.
- Smoke released from forest fires.
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