Photochemical smog is formed when primary pollutants interact with __. a. sunlight b. carbon c. water vapor d. sulfur dioxide e. oxygen
The Correct Answer and Explanation is:
The correct answer is a. sunlight.
Photochemical smog is a type of air pollution that forms when primary pollutants in the atmosphere, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs), interact with sunlight. The process begins with the emission of these pollutants from sources like vehicle exhaust, industrial activities, and the burning of fossil fuels. When these pollutants are exposed to sunlight, they undergo a series of complex chemical reactions that result in the formation of secondary pollutants, including ozone (O3), which is a key component of photochemical smog.
The sunlight provides the necessary energy to drive these chemical reactions. Specifically, ultraviolet (UV) radiation from the sun breaks down nitrogen dioxide (NO2) into nitric oxide (NO) and a free oxygen atom (O). This free oxygen atom then reacts with molecular oxygen (O2) to produce ozone (O3). Additionally, VOCs released from sources like gasoline and solvents contribute to the formation of other harmful compounds like peroxyacetyl nitrates (PANs).
The presence of ozone in photochemical smog is particularly problematic because it is a strong oxidizing agent that can irritate the respiratory system, reduce lung function, and cause eye irritation. In high concentrations, it can also damage vegetation and reduce agricultural productivity. As a result, photochemical smog is not only a significant environmental issue but also a public health concern, particularly in urban areas with high levels of vehicle emissions and industrial activity.
In summary, photochemical smog forms when sunlight interacts with primary pollutants like nitrogen oxides and VOCs, driving the chemical reactions that produce secondary pollutants, primarily ozone. This highlights the importance of controlling emissions to reduce smog formation.
