You've probably heard of "acid
rain". But you may not have heard of acid snow, acid fog or mist, acid
gas and acid dust. All of these "acids" are related air pollutants,
and can harm your health, cause hazy skies and damage the environment and your
property. The 1990 Clean Air Act includes an innovative program to reduce acid
air pollutants (all referred to here as "acid rain").
The acid rain that has received the most
attention is caused mainly by pollutants from big coalburning power plants in
the Midwest. These plants burn Midwestern and Appalachian coal, some of which
contains a lot of sulfur compared to Western coal. Sulfur in coal becomes
sulfur dioxide (S02) when coal is burned. Big power plants burn large
quantities of coal, so they release large amounts of sulfur dioxide, as well
as NOx (nitrogen oxides). These are acid chemicals, related to two strong
acids: sulfuric acid and nitric acid.
The sulfur dioxide and nitrogen oxides
released from the Midwestern power plants rise high into the air and are
carried by winds toward the East Coast of the U.S. and Canada. When winds blow
the acid chemicals into areas where there is wet weather, the acids become
part of the rain, snow or fog. In areas where the weather is dry, the acid
chemicals may fall to Earth in gases or dusts.
Lakes and streams are normally slightly
acid, but acid rain can make them very acid. Very acid conditions can damage
plant and animal life.
Acid lakes and streams have been found
all over the country. For instance, lakes in Acadia National Park on Maine's
Mt. Desert Island have been very acidic, due to pollution from the Midwest and
the East Coast. Streams in Maryland and West Virginia, lakes in the Upper
Peninsula of Michigan, and lakes and streams in Florida have also been
affected by acid rain. Heavy rainstorms and melting snow can cause temporary
increases in acidity in lakes and streams in the eastern and western United
States. These temporary increases may last for days or even weeks.
Acid rain has damaged trees in the
mountains of Vermont and other states. Red spruce trees at high altitudes
appear to be especially sensitive to acid rain. The pollutants that cause acid
rain can make the air hazy or foggy; this has occurred in the eastern United
States, including some mountain areas popular with vacationers, such as the
Great Smokies.
Acid rain does more than environmental
damage; it can damage health and property as well. Acid air pollution has been
linked to breathing and lung problems in children and in people who have
asthma. Even healthy people can have their lungs damaged by acid air
pollutants. Acid air pollution can eat away stone buildings and statues.
Health, environmental and property
damage can also occur when sulfur dioxide pollutes areas close to its source.
Sulfur dioxide pollution has been found in towns where paper and wood pulp are
processed and in areas close to some power plants. The 1990 Clean Air Act's
sulfur dioxide reduction program will complement health-based sulfur dioxide
pollution limits already in place to protect the public and the environment
from both nearby and distant sources of sulfur dioxide.
The Act takes a new nationwide approach
to the acid rain problem. The law sets up a marketbased system designed
to lower sulfur dioxide pollution levels. Beginning in the year 2000, annual
releases of sulfur dioxide will be about 40 percent lower than the 1980
levels. Reducing sulfur dioxide releases should cause a major reduction in
acid rain.
Phase I of the acid rain reduction
program goes 4 into effect in 1995. Big coal-burning boilers in 110 power
plants in 21 Midwest, Appalachian, Southeastern and Northeastern states will
have to reduce releases of sulfur dioxide. In 2000, Phase II of the
acid rain program goes into effect, further reducing the sulfur dioxide
releases from the big coal-burning power plants and covering other smaller
polluters. Total sulfur dioxide releases for the country's power plants will
be permanently limited to the level set by the Clean Air Act for the year
2000.
Reductions in sulfur dioxide releases
will be obtained through a program of emission (release) allowances.
EPA will issue allowances to power plants covered by the acid rain program;
each allowance is worth one ton of sulfur dioxide released from the
smokestack. To obtain reductions in sulfur dioxide pollution, allowances are
set below the current level of sulfur dioxide releases. Plants may only
release as much sulfur dioxide as they have allowances. If a plant expects to
release more sulfur dioxide than it has allowances, it has to get more
allowances, perhaps by buying them from another power plant that has reduced
its sulfur dioxide releases below its number of allowances and therefore has
allowances to sell or trade. Allowances can also be bought and sold by
"middlemen", such as brokers, or by anyone who wants to take part in
the allowances market. Allowances can be traded and sold nationwide. There are
stiff penalties for plants which release more pollutants than their allowances
cover.
The acid rain program provides bonus
allowances to power plants for (among other things) installing clean coal
technology that reduces sulfur dioxide releases, using renewable energy
sources (solar, wind etc.) or encouraging energy conservation by customers so
that less power needs to be produced.
All power plants under the acid rain
program will have to install continuous emission monitoring systems (CEMS),
machines that keep track of how much sulfur dioxide and nitrogen oxides the
plant is releasing. A power plant's program for meeting its sulfur dioxide and
nitrogen oxide limit will appear on the plant's permit, which will be
filed with the state and EPA.
To cut down on nitrogen oxide pollution,
EPA will require power plants to reduce their nitrogen oxide releases, and
will require reductions in nitrogen oxide releases from new cars. Reducing
nitrogen oxide releases will reduce both acid rain and smog formation.
The flexible market-based acid rain
reduction program is expected to be a model for pollution control efforts in
the United States and other countries.
