Practice question

Los Angeles-type smog is oxidising photochemical smog, and ground-level ozone is one of its major components. Strong sunlight drives reactions among nitrogen oxides and volatile organic compounds emitted chiefly by traffic and industry. Sulfur dioxide is more characteristic of traditional coal-smoke or London smog, whereas carbon monoxide may be present but does not define this smog type. The distinction is ecologically important because emission control must target either the directly released precursor or the product formed after atmospheric transport and reaction. Exposure depends on concentration, duration, ventilation, weather, and individual susceptibility, so a pollutant's presence alone does not fully predict biological harm. Atmospheric inversions can trap contaminants near the surface, while wind, turbulence, precipitation, and chemical transformation determine their eventual distribution and removal. At organismal level, respiratory surfaces are especially exposed because large volumes of air contact thin, moist epithelia designed for rapid gas exchange. Sound classification links the source, atmospheric fate, exposure route, and mechanism of toxicity rather than relying only on the pollutant's name.