Why is it advised that industries should switch over to cleaner fuels such as CNG and LPG in the Taj Mahal Zone in Agra?

Explanation

### Step-by-Step Solution:

1. **Understanding the Problem**: The Taj Mahal, a UNESCO World Heritage Site, is facing discoloration due to air pollution, particularly from harmful emissions produced by industries and vehicles using fossil fuels like petrol and diesel.

2. **Identifying Harmful Emissions**: When fossil fuels are burned, they release harmful gases such as carbon monoxide (CO) and carbon dioxide (CO2). These gases can react in the atmosphere to form other harmful compounds, including sulfur oxides and nitrogen oxides.

3. **Formation of Acid Rain**: The sulfur oxides and nitrogen oxides produced can combine with water vapor in the atmosphere to form sulfuric acid and nitric acid. When it rains, these acids fall to the ground as acid rain.

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