EPA's Efforts to Reduce SO2
Sulfur Dioxide
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Reducing emissions of SO2 remains a crucial component of EPA's strategy for cleaner air. Meeting EPA's national health-based air quality standards is an important step towards ensuring the air is safe to breathe. To meet the standards, EPA, states, tribes, and local governments work as partners to reduce emissions of SO2 through several control programs.
EPA has three major objectives in reducing emissions of sulfur dioxide:
National health-based air quality standards
Meeting the national ambient air quality standards for sulfur dioxide
entails working with state and local governments to ensure that
the levels of SO2 in the air are not unhealthy.
Breathing SO2 can cause respiratory illness and aggravate
existing heart and lung diseases.
Reducing acid rain
SO2 is a primary contributor to the formation of acid rain,
which is associated with acidification of soils, lakes, and streams, and
accelerated corrosion of buildings and monuments. To help reduce
acid rain, EPA is implementing a program to reduce releases of SO2 and
other pollutants from coal-fired power plants. The first phase began
in 1995 for SO2 and targets the largest and highest emitting
power plants. The second phase (started in 2000) sets tighter restrictions
on smaller coal-, gas-, and oil-fired plants. This program will reduce
annual SO2 emissions by 10 million tons (almost half the 1980
level) between 1980 and 2010.
Reducing the formation of particulate
matter
Particulate matter can be formed from direct sources (like diesel exhaust
or smoke), but can also be formed through chemical reactions. Emissions
of SO2 can be chemically transformed into ammonium sulfates,
which are very tiny particles that can be carried by winds hundred of miles.
These small particles have been shown to cause a series of health problems
for asthmatics, the elderly, and other people with pre-existing respiratory
problems. These same small particles are also a main pollutant that impairs
visibility across large areas of the country, particularly national parks
that are known for their scenic views.
The nation has made great steps forward in meeting the first goal of meeting the national air quality standards. Levels of SO2 in the air have decreased over the past 20 years. These reductions over time were accomplished by installing pollution control equipment at coal-fired power plants, reducing pollution from industrial processing facilities, reducing the average sulfur content of fuels burned, and using cleaner fuels like natural gas for residential and commercial heat. However, further reductions of SO2 and other pollutants will likely be needed to solve the particulate matter and acid rain problems.
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