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Given our country’s reliance on fossil fuels for power production and
the increase in vehicle use, it is perhaps not surprising that many people believe
that air quality in the United States has declined in recent years. Of those
surveyed, almost half (47.6 percent) indicated that U.S. air quality has gotten
worse since 1970. Only 27.5 percent responded that air quality in the U.S. has
improved significantly since then.
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In spite of the twentieth
century's steep population rise, massive industrialization,
and the nationwide proliferation of the modern automobile,
the air we breathe is cleaner than it has been in decades.
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Statistics reveal, however, that the latter are correct.
Data from the Environmental Protection Agency also confirm
that U.S. air quality has improved since 1970. The six commonly
found, or “criteria” air pollutants—PM2.5 particulate
matter, sulfur dioxide, nitrogen oxide, volatile organic compounds,
carbon monoxide, and lead—have decreased by more than
50 percent; air toxins from large industrial sources, such
as chemical plants, petroleum refineries, and paper mills
have been reduced by nearly 70 percent; new cars are more
than 90 percent cleaner in terms of their emissions; and production
of most ozone-depleting chemicals has ceased. Meanwhile, gross
domestic product has tripled, energy consumption has increased
50 percent, and motor vehicle use has increased by almost
200 percent.[82] However, if carbon-dioxide
emissions are counted as pollution,[83]
then overall pollution numbers certainly look quite different,
as our country’s carbon emissions rose throughout the
twentieth century.
According to air-quality expert Joel Schwartz, average levels of air pollution
fell between 20 percent and 96 percent between 1980 and 2005, depending on the
pollutant.[84]
Schwartz notes that Americans are driving, producing, and using more energy
than ever before, yet “air quality in America’s cities is better than
it has been in more than a century—despite the fact that the U.S. population
has almost quadrupled and real GDP has risen by a factor of nearly thirty.”[85]
 Author
and journalist Gregg Easterbrook states that aggregate air
emissions have fallen 25 percent since 1970, while the population
increased 39 percent during the same period.[86]
More recently, the combined emissions of the six criteria
pollutants dropped 41 percent from 1990 to 2007, all “while
the U.S. economy continued to grow, Americans drove more miles,
and population and energy use increased.”[87]
In his book The Progress Paradox, Easterbrook writes that smog has declined
by one-third since 1970, though the number of motor vehicles has nearly doubled
and vehicle-miles traveled have increased by 143 percent. Easterbrook also documents
that acid rain—precipitation with elevated acidity levels that results
from such activities as coal combustion and is thought to contaminate plants
and fresh water—has declined by two-thirds, though the U.S. burns almost
twice as much coal each year; and airborne lead, a poison, is down 97 percent.[88]
How has the U.S. seen such growth, both in terms of population and economically,
while also reducing air pollution? Many credit the federal
Clean Air Act (CAA), adopted in 1970 to curb pollution, while
others point out that air quality was improving prior to the
passage of the CAA. For example, Schwartz writes: “Nationwide
monitoring data demonstrate that particulate levels declined
nearly 20 percent between 1960 and 1970, while sulfur dioxide
declined more than 30 percent.”[89]
In spite of the twentieth century’s steep population
rise, massive industrialization, and the nationwide proliferation
of the modern automobile, the air we breathe is cleaner than
it has been in decades.
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