SO2
SO2 belongs to the family
of sulfur oxide gases (SO2).
These gases dissolve easily in water. Sulfur is prevalent in all raw materials,
including crude oil, coal, and ore that contains common metals like aluminum, copper,
zinc, lead, and iron. SO2
gases are formed when fuel containing sulfur, such as coal and oil, is burned, and
when gasoline is extracted from oil, or metals are extracted from ore. SO2 dissolves in water vapor to form acid, and interacts with
other gases and particles in the air to form sulfates and other products that can
be harmful to people and their environment.
SO2 contributes to respiratory
illness, particularly in children and the elderly, and aggravates existing heart
and lung diseases.
SO2 contributes to the
formation of acid rain, which:
- damages trees, crops, historic buildings, and monuments; and
- makes soils, lakes, and streams acidic
SO2 contributes to the
formation of atmospheric particles that cause visibility impairment, most noticeably
in national parks.
SO2 and the pollutants
formed from SO2, such
as sulfate particles, can be transported over long distances and deposited far from
the point of origin. This means that problems with SO2 are not confined to areas where it is emitted.
High levels of SO2 over
a short period, such as a day, can be particularly problematic for people with asthma.
EPA encourages communities to learn about the types of industries in their communities
and to work with local industrial facilities to address pollution control equipment
failures or process upsets that could result in peak levels of SO2
SO2 causes a wide variety
of health and environmental impacts because of the way it reacts with other substances
in the air. Particularly sensitive groups include people with asthma who are active
outdoors and children, the elderly, and people with heart or lung disease. |
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Peak levels of SO2 in
the air can cause temporary breathing difficulty for people with asthma who are
active outdoors. Longer-term exposures to high levels of SO2
gas and particles cause respiratory illness and aggravate existing heart disease.
SO2 reacts with other
chemicals in the air to form tiny sulfate particles. When these are breathed, they
gather in the lungs and are associated with increased respiratory symptoms and disease,
difficulty in breathing, and premature death.
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Haze occurs when light is scattered or absorbed by particles and gases in the air.
Sulfate particles are the major cause of reduced visibility in many parts of the
U.S., including our national parks. |
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SO2 and nitrogen oxides
react with other substances in the air to form acids, which fall to earth as rain,
fog, snow, or dry particles. Some may be carried by the wind for hundreds of miles. |
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Acid rain damages forests and crops, changes the makeup of soil, and makes lakes
and streams acidic and unsuitable for fish. Continued exposure over a long time
changes the natural variety of plants and animals in an ecosystem. |
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SO2 accelerates the decay
of building materials and paints, including irreplaceable monuments, statues, and
sculptures that are part of our nation's cultural heritage. |