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

Explanation

Smong is a kind of air pollution. It is the blend of smoke and fog. There are two king of smog:
a) Classical smog
b) Photochemical smog
The two smogs can be differentiated as follows:
`{:(,"Clasical smog","Photochemical smog"),("Occurence"," It occurs in a cood, humid climate"," It occurs in a dry, sunny climate"),("Components"," Smoke, fog, and sulphurdioxide."," PAN, acrolein, Ozone, formalhyde, nitric oxide."),(" Nature"," It is reducing in nature"," It is oxidizing in nature"):}`