Lesson 82: Bringing Air Pollution Under Control
In this lesson,
we will talk about the federal government's efforts to control air pollution
through the Clean Air Act and through standards it has set for motor vehicle
emissions. We will also look at efforts to reduce acid deposition.
Federal legislation to combat air pollutants came in
the form of the 1970 Clean Air Act. The Clean Air Act (CAA) identified air
pollutants, set standards, and established methods of control and timetables to
meet those standards.
The NAAQS or National Ambient Air Quality Standards set standards for four
primary pollutants - particulates, sulfur dioxide, carbon monoxide and nitrogen
oxide.
Motor vehicles generate a lot of air pollutants that foul the air such as VOCs,
carbon monoxide and nitrogen oxides.
Today's cars have reduced 90% of emissions compared to
1970. The catalytic converter is the primary pollution-control device. It
converts nitrogen oxide into harmless nitrogen gas and converts unburned
hydrocarbons and carbon monoxide into carbon dioxide.
In 1975,
the government created the corporate average fuel economy (CAFE) standards for
motor vehicles. This was set at 27.5 mpg for passenger cars in 1984 and 20.7
mpg for trucks. These standards were raised in 2007 to be 35 mpg for cars and
light trucks by 2020. This was done to reduce dependence on foreign oil and
increase use of renewable energy with lowered GHGs.
Motor vehicles release VOCs and
nitrogen dioxide. The ozone is affected by emissions of these gases.
Scientists working on acid rain issues calculated that
a 50% reduction would prevent further acidification of the environment.
Power plants contribute to acid rain significantly. Controlling emissions from
power plants was determined to be the best way to
reduce acid rain. However, in the 1980s, interest groups representing power
plants in the Midwest blocked all legislation against acid rain.
It took almost another decade, but the passage of Title IV of the Clean Air Act
Amendments of 1990 required reductions in sulfur dioxide and nitrogen oxide. To
meet these requirements, utility companies had to adapt. Some switched to
low-sulfur coal and others added scrubbers to prevent sulfur dioxide from
entering the air directly. Others traded emission allowances. Health benefits
from reducing acid rain have been estimated at $174 to $427 billion in 2010.
Visibility has increased significantly in these areas as well.