Using the examples of Tehran and Los Angeles, discuss the special problems that vehicles create for urban outdoor air pollution

Question

What will be an ideal response?

Answer 1

Tehran and Los Angeles are sister cities that have one important thing in common, photochemical smog. Photochemical smog is a mixture of primary (nitrogen oxides and VOCs) and secondary pollutants (tropospheric ozone and more than 100 different toxic derivatives from their interaction in the presence of solar UV light). Both cities have geographic conditions that promote the formation of thermal inversions which can trap the smog near the ground for long periods of time and produce dangerously high concentrations of pollutants. The result is an assault of human respiratory systems that in both cities causes thousands to die premature deaths.
Los Angeles has greatly improved the levels of smog by developing mass transit and by requiring strict pollution control technologies on vehicles. Expensive gasoline has made fuel-efficient vehicles popular. In Tehran, with very cheap gasoline available to all, millions of inefficient, gas-guzzling vehicles, most without any pollution control devices, produce smog that was typical of the Los Angeles area 30 years ago. Tehran's mass transit is poorly developed, forcing citizens with modest incomes to rely on motorcycles, cars and taxis. Both cities struggle with the same problems with continuing pressure from the public to improve air quality.