What is the difference between fog and smog?

Last updated at July 29, 2026 by

Fog is caused by water droplets in the air. But, Smog - Smog is Smoke + Fog.

It is a sign of severe air pollution.

Look at the image below of a city in China, notice the effect of smog in the atmosphere.

Effect of Smog.png

 

Let's discuss the differences between Fog and Smog

Fog Smog
Fog is caused by water droplets in the air Smog is made up of Smoke and Fog
It reduces visibility, but breathing in fog causes no harm.  Breathing in Smog can cause Eye Irritation, Asthma and decreases Lung's Breathing Capacity
Color of fog is white Color of Smog is usually blackish, but may change depending on other pollutants in the atmosphere 

fog-vs-smog---teachoo.jpg

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Maninder Singh

CA Maninder Singh is a Chartered Accountant with 16+ years of practical experience and 20+ years of teaching experience. He teaches Science, Economics, Accounting and English at Teachoo using clear explanations and exam-focused methods students can trust.

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