Question

Brown air is due to:

• A. CO₂
• B. SO₂
• C. CH₄
• D. NO_x

Hint:

To prevent the formation of brown air, reducing emissions from vehicles and industrial sources that release NOx and VOCs is essential, along with promoting cleaner technologies and fuels.

Answer 1

The Correct Option is D

Brown air, also known as photochemical smog, is primarily caused by the presence of nitrogen oxides (NO_x) in the atmosphere, along with volatile organic compounds (VOCs). When sunlight reacts with these pollutants, it leads to the formation of ground-level ozone and other secondary pollutants, which give the air a brownish appearance.
CO₂ (Carbon dioxide) is a greenhouse gas that contributes to global warming but does not directly cause brown air.
SO₂ (Sulfur dioxide) contributes to acid rain but is more associated with the formation of gray air rather than brown air.
CH₄ (Methane) is a potent greenhouse gas and contributes to air pollution, but it is not directly responsible for brown air.

Thus, the presence of NO_x in combination with VOCs is the main cause of brown air (photochemical smog).