From the urban population data, which month most likely experiences the highest photochemical smog?

From the urban population data, which month most likely experiences the highest photochemical smog?

• A. January
• B. April
• C. October
• D. July

Answer: (D)

Photochemical smog forms when sunlight drives reactions between pollutants such as nitrogen oxides from vehicle exhaust and volatile organic compounds, producing ozone and other oxidants. The intensity of these reactions depends on how much sunlight and heat there is. More sunlight and warmer temperatures speed up the chemical processes that create ozone, so summers tend to have the most photochemical smog. In winter, less daylight and cooler conditions slow these reactions, reducing smog formation. Spring and autumn have moderate sunlight, but not as much as midsummer. Therefore, the month with the highest photochemical smog in urban areas is the peak of summer, when sunlight is strongest and temperatures are highest.

Photochemical smog forms when sunlight drives reactions between pollutants such as nitrogen oxides from vehicle exhaust and volatile organic compounds, producing ozone and other oxidants. The intensity of these reactions depends on how much sunlight and heat there is. More sunlight and warmer temperatures speed up the chemical processes that create ozone, so summers tend to have the most photochemical smog. In winter, less daylight and cooler conditions slow these reactions, reducing smog formation. Spring and autumn have moderate sunlight, but not as much as midsummer. Therefore, the month with the highest photochemical smog in urban areas is the peak of summer, when sunlight is strongest and temperatures are highest.