🌱 Environment & EcologyUPSC 2013Sustainable Development

Photochemical smog is a resultant of the reaction among

aNO2, O3 and peroxyacetyl nitrate in the presence of sunlight
bCO, O2 and peroxyacetyl nitrate in the presence of sunlight
cCO, CO2 and NO2 at low temperature
dhigh concentration of NO2, O3 and CO in the evening
✓ Correct answer: a) NO2, O3 and peroxyacetyl nitrate in the presence of sunlight
ExplanationPhotochemical smog, often referred to as “Los An- geles smog,” is most commonly found in urban areas with high numbers of automobiles.It does not require smoke or fog to form.This type of smog is formed from the nitrogen oxides and hydrocarbon (peroxyacetyl nitrate, a hazardous pollutant) vapors released by vehicles and other sources, which then un- dergo photochemical reactions in the lower atmosphere in the presence of sunlight.94

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