Question

What is smog?

1) Smog is the combination of smoke and fog resulting in polluted air.
2) Smog is the smoke resulting in polluted air.
3) Smog is the fog resulting in polluted air.
4) None of the above.

Answer 1

Smog is the result of the combination of smoke and fog, leading to polluted air—option 1 is the correct answer. It consists of sulfur dioxide, nitrogen oxides, ozone, and particulates, and forms primarily due to combustion of fossil fuels in urban areas.

Step-by-step explanation:

Smog is a type of air pollution that is a combination of smoke and fog, resulting in polluted air, which makes option 1) the correct answer. It is formed by a mixture of air pollutants—specifically, sulfur dioxide, nitrogen oxides, ozone, and particulates—often over urban areas due to fossil fuel combustion. There are chiefly two types of smog: industrial and photochemical. Industrial smog is created from the burning of fossil fuels, leading to substances such as carbon dioxide, carbon monoxides, sulfur, and mercury. The sulfur reacts with atmospheric chemicals, forming sulfur compounds like sulfur dioxide which, combined with particulates, comprise industrial smog.

Photochemical smog, on the other hand, occurs when sunlight drives chemical reactions between primary pollutants, usually from automobile emissions, and normal atmospheric compounds, producing a mix of over 100 different chemicals, predominantly ground-level ozone. Major contributors to the formation of smog include nitrogen compounds, collectively referred to as NOx, which arise from high-temperature combustion processes in modern automobile engines. This smog poses significant health risks, reducing visibility and affecting the respiratory systems of exposed populations.