SO2 - How Sulfur Dioxide
Affects the
Way We Live & Breathe
| Sulfur dioxide, or SO2, belongs to
the family of sulfur oxide gases (SOx). 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. SOx 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.
Over 65% of SO2 released to the air, or more than 13
million tons per year, comes from electric utilities, especially those
that burn coal. Other sources of SO2 are industrial
facilities that derive their products from raw materials like metallic
ore, coal, and crude oil, or that burn coal or oil to produce process
heat. Examples are petroleum refineries, cement manufacturing, and
metal processing facilities. Also, locomotives, large ships, and some
nonroad diesel equipment currently burn high sulfur fuel and release
SO2 emissions to the air in large quantities.
courtesy of EPA - Environmental Protection Agency
|
SO2
contributes to respiratory illness, particularly in children and the
elderly, and aggravates existing heart and lung diseases.
SO2contributes 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 can be transported over
long distances.
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. |

People with asthma are particularly
affected by peak levels of SO2.
[courtesy of EPA - Environmental Protection
Agency] |
Short-term Peak
Levels
High levels of SO2emitted 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. |
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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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Respiratory Effects from
Gaseous SO2
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.
Respiratory Effects from Sulfate Particles
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. |
![Visibility Impairment [courtesy of EPA - Environmental Protection Agency]](images/eye.gif) |
Visibility Impairment
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. |
![acid rain [courtesy of EPA - Environmental Protection Agency]](images/acidrain.gif) |
Acid Rain
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. |
![Plant and Water Damage [courtesy of EPA - Environmental Protection Agency]](images/aquaveg.gif) |
Plant and Water Damage
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. |
![Aesthetic Damage [courtesy of EPA - Environmental Protection Agency]](images/monument.gif) |
Aesthetic Damage
SO2 accelerates the decay of building materials and paints,
including irreplaceable monuments, statues, and sculptures that are
part of our nation's cultural heritage. |
Reference:
http://www.epa.gov/air/urbanair/so2/index.html |