classical smog and photo chemical smog

What is smog? How is classical smog different from photochemical smogs?

Solution:
Smog is a combination of 'smoke' and 'fog'. This is because it is formed for the first time due to
the condensation of some kind of fog on the carbon particles present in the smoke produced
due to combustion of domestic fuels and industrial fuels like coal and petroleum.

Difference between classical smog and photo chemical smog:

Classical Smog
1. This type of smog was first observed in London in 1952.
2. It involves smoke and fog.
3. This type of smog is formed due to the presence of SO and humidity in the air which combines to from H SO fog which deposits on the particles.
4. It is formed in the month of winter particularly in the morning hour when the temperature is low.
5. It causes bronchitis, irritations; problems in the lungs.
6. It is reducing in character.

Photochemical Smog
1. This type of smog was observed in Los Angeles in 1950.
2. It does not involves any smoke or fog. The word smog is misnomer here.
3. It is formed due to the photochemical reactions taking place when air combines with NO and
hydrocarbons.
4. It is formed in the month of summer during afternoon when there is bright sunlight so that
photochemical reactions can take place.
5. It causes irritation in the eyes.
6. It is oxidizing in character.