Photochemical Smog and its Precursors

Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants such as hydrocarbons and nitrogen oxides in the atmosphere. The primary precursor of photochemical smog is nitrogen dioxide (NO2).

Explanation

Here is the detailed explanation of why NO2 is the primary precursor of photochemical smog:

• Nitrogen dioxide (NO2) is a highly reactive gas that is produced by the combustion of fossil fuels, especially in vehicles and power plants.

• When NO2 is exposed to sunlight, it undergoes a series of chemical reactions that produce other pollutants such as ozone (O3) and peroxyacetyl nitrate (PAN).

• Ozone and PAN are the primary components of photochemical smog, which is a brownish haze that can be seen in many cities during the summer months.

• In addition to NO2, other precursors of photochemical smog include volatile organic compounds (VOCs) such as benzene, toluene, and xylene. These compounds are also produced by the combustion of fossil fuels and can react with NO2 in the presence of sunlight to form ozone and PAN.

• The formation of photochemical smog is a complex process that depends on many factors, including temperature, humidity, and wind speed. However, the primary precursor is always NO2.

Conclusion

In conclusion, nitrogen dioxide (NO2) is the primary precursor of photochemical smog. When NO2 reacts with sunlight, it produces other pollutants such as ozone and peroxyacetyl nitrate, which are the main components of photochemical smog. Other precursors of photochemical smog include volatile organic compounds (VOCs), but NO2 is the most important one.

Photochemical smog is a type of smog produced when ultraviolet light from the sun reacts with nitrogen oxides in the atmosphere. It is visible as a brown haze, and is most prominent during the morning and afternoon, especially in densely populated, warm cities.