The correct option is Fog and smoke.
Explanation
The term "Smog" is a portmanteau derived from the combination of two words: Smoke and Fog. It refers to a form of air pollution produced by the interaction of sunlight with certain chemicals in the atmosphere or the mixture of particulate matter with condensed water vapor.
Detailed Analysis:
- Composition: Smog is traditionally defined as a mixture of smoke (containing particulates, sulfur dioxide, and other pollutants) and fog (suspended water droplets near the ground).
- Historical Context: The term was first coined by Dr. Henry Antoine Des Voeux in 1905 to describe the smoky fog prevalent in London due to coal burning.
- Types of Smog:
- Classical Smog (London Smog): Occurs in cool, humid climates and is a mixture of smoke, fog, and sulfur dioxide. It is chemically reducing in nature.
- Photochemical Smog (Los Angeles Smog): Occurs in warm, dry, and sunny climates. It results from the action of sunlight on unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories. It is oxidizing in nature.
Key Takeaway:
Smog is an atmospheric condition characterized by the mixture of smoke and fog, leading to reduced visibility and respiratory health hazards.