Vehicle Emissions and Emissionless Vehicles

Vehicle exhaust contributes to three of the most serious pollution problems in the world today: acid rain (Chapter 27), global warming (Chapter 29), and photochemical smog, the topic of this chapter. Photochemical smog rst entered the public’s consciousness in the 1940s, especially in Los Angeles. Smog can be so irritating to the eyes and respiratory tract that, during the Second World War, some people thought the smog was actually a poison gas attack by the Japanese military. Within twenty years, smog was stunting tree growth eighty kilometers from the city center. By 1976, Los Angeles’ air had reached ofcially unhealthy levels about 75% of the time, or three days out of every four.