Differentiate Primary and secondary pollutant.

Explanation

### Step-by-Step Solution:

1. **Definition of Primary Pollutants**:
- Primary pollutants are substances that are released directly into the environment in their original form. They do not undergo any chemical change after being emitted.
- Example: Carbon monoxide (CO), sulfur dioxide (SO₂), and nitrogen oxides (NOx) are considered primary pollutants because they enter the atmosphere directly from sources like vehicle emissions, industrial processes, or combustion.

2. **Characteristics of Primary Pollutants**:
- They persist in the environment without undergoing any transformation.
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