What are primary and secondary pollutants of the air ?

Explanation

### Step-by-Step Text Solution:

1. **Definition of Primary Pollutants**:
- Primary pollutants are substances that are directly emitted into the atmosphere from various sources. They do not undergo any transformation before entering the air.

2. **Characteristics of Primary Pollutants**:
- They are typically less toxic compared to secondary pollutants.
- They are emitted directly from sources such as vehicles, industries, and natural sources.
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