EPA's Efforts to Reduce SO₂

Sulfur Dioxide

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.

For more information:

EPA's Efforts to Reduce SO2

Sulfur Dioxide

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EPA's Efforts to Reduce SO₂