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Which of the following types of smog is primarily caused by photochemical reactions?

Option: 1

Industrial smog

Option: 2

London smog

Option: 3

Los Angeles smog

Option: 4

None of the above

Answers (1)


The type of smog that is primarily caused by photochemical reactions is Los Angeles smog, also known as "photochemical smog" or "brown smog."

Photochemical smog is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight to form ground-level ozone (O_3) and other secondary pollutants such as aldehydes and peroxyacyl nitrates (PANs). NO_x  and VOCs are primarily emitted by motor vehicles and industrial processes.

The formation of photochemical smog is a complex process that involves a series of chemical reactions. Initially, NO_x  and VOCs are emitted into the atmosphere, where they are subjected to sunlight and react to form ozone and other secondary pollutants. The reaction of NO_x  with sunlight produces nitrogen dioxide (NO_2), which can further react with VOCs to form O_3 and other secondary pollutants. The secondary pollutants can cause respiratory problems, eye irritation, and other health problems.

Los Angeles is known for its photochemical smog, which is caused by the large number of motor vehicles in the area and the high levels of sunlight. The city's geography, with its surrounding mountains, also contributes to the formation of smog by trapping pollutants in the area.

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