Smog is a weather phenomenon which has posed a lot of health hazards for living organisms. The combination of the words smoke and fog gives rise to smog which is actually a major form of air pollution. It is produced by the burning of fuels like coal in huge quantities in a certain area. The resultant emission which is sulfur dioxide and smoke gives rise to smog .

Origin of Smog :

The word smog was introduced by Dr. H.A. Des Voeux in 1905. Photochemical smog was another term which was used in the 1950's to describe a mixture of toxic air pollutants like oxides of nitrogen, aldehydes, volatile organic compounds, peroxyacyl nitrates and tropospheric ozone. Photochemical smog is caused by the chemical action that takes place between air pollutants and the sun. It results in the formation of particulate matter and ground level ozone.

Causes of Smog :

•  Industrialization, which requires the burning of fossil fuel results in smog .

•  There can be natural causes of smog like volcanic eruptions.

•  Forest fires can also lead to smog .

Places Affected by Smog :

Smog affects areas where there is profound industrial activity and a lot of air pollution. The problem aggravates during summer when vertical circulation of air is restricted. It often lasts for a long time in densely populated areas like busy cities. Cities like London, Beijing, New York, Los Angeles, Hong Kong, Houston and Mexico City have risky levels of smog .

Health Hazards of Smog :

•  Smog can often lead to serious diseases of the lungs and heart like Asthma, Bronchitis and Emphysema

•  It can also irritate the nose and eye.

•  It reduces the body's immunity.

Smog is a dangerous kind of air pollution which is a matter of great concern in the modern era.