Page 487 - Environment: The Science Behind the Stories

California took the lead among U.S. states in adopting old polluting cars for newer cleaner ones. Sulfur was reduced
pollution control technology and setting emissions standards in diesel fuel, lead was removed from gasoline, and buses run-
for vehicles. California’s demands helped lead the auto indus- ning on (cleaner-burning) natural gas hit the roads. To raise
try to develop less-polluting cars. A 2010 study by the non- public awareness, 22 real-time pollution indicator boards were
profit group Environment California concluded that a new installed around the city, electronically displaying current pol-
car today generates just 1% of the smog-forming emissions lutant levels. All these efforts helped reduce pollution, yet so
of a 1960s-era car. Because today’s cars are 99% cleaner, many people were streaming into the city and buying cars that
the air is cleaner, even with more drivers on the road. In Los these trends overtook the government’s efforts, and pollution
Angeles, peak smog levels have decreased 60–70% since grew worse again after 2006. In response, officials lowered
1980 (Figure 17.23). In 2012, researchers added that VOCs gasoline subsidies, rationed fuel, began expanding the subway
in L.A.’s air had declined by 98% since 1960, even while the system, and strengthened some previous programs.
city’s drivers burned 2.7 times more gasoline. Of all the world’s cities, Mexico City is gaining atten-
Today in California and 33 other states, drivers are tion today for its success in reducing smog—once the world’s
required to have their vehicle exhaust inspected periodically. worst—even as population, cars, and economic activity have
Vehicle inspection programs have cut emissions leading to grown. Regulations now require cars to have catalytic convert-
photochemical smog by 30% in many of these states, helping ers and get emissions tests. Some industrial facilities cleaned
to make the air measurably cleaner for all of us. up their processes, and others were forced out. Under pressure
Despite its progress, Los Angeles still suffers the from city leaders, the national oil company Pemex removed
worst tropospheric ozone pollution of any U.S. metropoli- lead from gasoline, improved its refineries, imported cleaner
tan area, according to 2012 rankings by the American Lung gasoline, and removed pollutants from the liquefied petroleum
Association. L.A. residents breathe air exceeding California’s gas that city residents use for cooking and heating. The sub-
health standard for ozone on more than 130 days per year. way system and a fleet of low-emission buses continue to be
A 2008 study calculated that air pollution in the L.A. basin expanded today, while residents begin using new bike-sharing
and the nearby San Joaquin Valley each year caused nearly and car-sharing programs. As a result, since 1990 smog has
3900 premature deaths and cost society $28 billion (due to been reduced by more than half, and particulate matter is
hospital admissions, lost workdays, etc.). down by 70%, carbon monoxide by 74%, sulfur dioxide by
Many of L.A.’s sister cities across the world also struggle 86%, and lead by 95%.
with photochemical smog and are working hard to develop
solutions. Athens, Greece, provides its citizens incentives
to replace aging vehicles and also mandates that autos with WeigHiNg tHe iSSUeS
odd-numbered license plates be driven only on odd-numbered SMOg-bUStiNg SOLUtiONS Does the city you live in, or the
days, and those with even-numbered plates only on even- nearest major city to you, suffer from photochemical smog or
numbered days. Smog has been reduced by 30% as a result. other air pollution? How is this city responding? What policies
In Tehran, Iran, vehicle inspections are required, traffic do you think it should pursue? What benefits might your city
into the city center is restricted, and drivers are paid to turn in enjoy from such policies? Would they bring any problems?

0.40
0.35 Ozone Depletion and Recovery
Peak 8-hour ozone level (ppm) 0.25 Although ozone in the troposphere is a pollutant in pho-
0.30

tochemical smog, ozone is a highly beneficial gas in the
0.20
stratosphere, where it forms the ozone layer (p. 469; see
Figure 17.2). In this region of the stratosphere, concen-
0.15
trations of ozone reach only about 12 parts per million.
0.10
However, ozone molecules are so effective at absorbing
Current California health standard
incoming ultraviolet (UV) radiation from the sun that even
0.05
this diffuse concentration helps to protect life on Earth’s
0.00 surface from radiation’s damaging effects.
1970 1980 1990 2000 2010 One generation ago, scientists discovered that our plan-
Year et’s stratospheric ozone was being depleted, posing a major
Figure 17.23 Peak levels of tropospheric ozone in the Los threat to human health and the environment. Years of dynamic
Angeles region have been reduced since the 1970s, thanks research by hundreds of scientists (see THe SCieNCe BeHiND THe
to public policy and improved automotive technology. Ozone STOrY, pp. 488–489) revealed that certain airborne chemi-
pollution still violates the state health standard, however. Data from cals destroy ozone and that most of these ozone-depleting
Environment California, 2010. Clean cars in California: Four decades of progress substances are human-made. Our subsequent campaign to
in the unfinished battle to clean up our air. halt degradation of the ozone layer stands as one of society’s
By what percentage has Los Angeles reduced its ozone most successful efforts addressing a major environmental
486 pollution since the 1970s? problem.

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