What do you understand by London smog and how is it formed?

Explanation

### Step-by-Step Solution:

1. **Definition of London Smog**:
- London smog, also known as "sulphurous smoke," is a type of air pollution that is characterized by a high concentration of sulfur oxides in the atmosphere.

2. **Formation of London Smog**:
- The primary components responsible for the formation of London smog are sulfur oxides, specifically sulfur dioxide (SO2) and sulfur trioxide (SO3).
- These sulfur oxides are released into the air mainly through the combustion of fossil fuels that contain sulfur, particularly coal.
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