SULFUR
DIOXIDE
Also
known as: SO2, sulfurous anhydride, sulfuroxide, sulfurous
oxide, sulfurous acid anhydride
Chemical
reference number (CAS): 7446-09-5
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What
is sulfur dioxide?
Sulfur dioxide, SO2, is a colorless gas or liquid with a
strong, choking odor. It is
produced from the burning of fossil fuels (coal and oil) and the smelting
of mineral ores (aluminum, copper, zinc, lead and iron) that contain
sulfur.
Sulfur
dioxide dissolves easily in water to form sulfuric acid.
Sulfuric acid is a major component of acid rain.
Acid rain can damage forests and crops, change the acidity of
soils, and make lakes and streams acidic and unsuitable for fish.
Sulfur dioxide also contributes to the decay of building materials
and paints, including monuments and statues.
Where
is sulfur dioxide found?
Most
of the sulfur dioxide released into the environment comes from electric
utilities, especially those that burn coal.
Some other sources of sulfur dioxide include petroleum refineries,
cement manufacturing, paper pulp manufacturing and metal smelting and
processing facilities. Locomotives,
large ships, and some non-road diesel equipment currently burn high sulfur
fuel and release sulfur dioxide into the air.
In nature, volcanic eruptions can release sulfur dioxide into the
air.
Some
dried fruits are preserved using SO2 to prevent discoloration
of the fruit. SO2
is also used in bleaching materials and as a fumigant. In
the home, sulfur dioxide gas can be found from tobacco smoke, improperly
or inadequately vented gas appliances (such as stoves, ranges, furnaces,
or clothes dryers), gas or kerosene heaters, wood or coal stoves, or
automobile exhaust.
How
can I be exposed to sulfur dioxide?
You
can be exposed to SO2 by breathing it in the air or getting it
on your skin. People who live
near industrial sources of sulfur dioxide may be exposed to it in the air.
You are most likely to be exposed if you work in industries where
SO2 is produced, such as copper smelting or power plants, or
where SO2 is used like the production of sulfuric acid, paper,
food preservatives or fertilizers. People
with malfunctioning appliances or chimneys in their homes may also be
exposed to sulfur dioxide.
Are
there health problems that can be caused by sulfur dioxide?
Although exposure to SO2
has not been shown to cause cancer in humans, there are serious health
problems related to both long and short term exposures.
Short term exposure to high enough levels of SO2 can be
life threatening. Generally,
exposures to SO2 cause a burning sensation in the nose and
throat. Also, SO2
exposure can cause difficulty breathing, including changes in the body’s
ability to take a breath or breathe deeply, or take in as much air per
breath. Long term exposure to
sulfur dioxide can cause changes in lung function and aggravate existing
heart disease. Asthmatics may
be sensitive to changes in respiratory effects due to SO2
exposure at even low concentrations.
How
can I reduce my exposure to sulfur dioxide?
To
reduce the possibility of exposure to sulfur dioxide caused by a source in
your home, you can:
-
Use
gas appliances with electronic (pilotless) ignition.
This will eliminate the continuous low-level pollutants from
pilot lights.
-
Use
exhaust fans over gas stoves that are vented to the outdoors instead
of fans that re-circulate the air indoors.
Keep the metal mesh filters on your exhaust fans clean (most
can be run through the dishwasher).
-
Choose
vented appliances whenever possible, and make sure they are vented to
the outdoors. Have a
trained professional inspect your appliances annually.
-
Never
heat your home with a gas range or stove.
-
Do
not idle your car in the garage.
-
Do
not smoke indoors.
Most
SO2 exposures are caused by people breathing contaminated
outdoor air. Therefore, limit
your activities outdoors when you know that air pollution levels are high.
The EPA and the Wisconsin Department of Natural Resources (DNR)
issue air quality alerts for high pollution days.
People with existing respiratory difficulties, like asthma, should
pay special attention to these air advisories.
Special care should be taken with child asthmatics to limit their
outdoor activities during high pollution days.
Other
Websites on Sulfur Dioxide (exit DHFS)
(PPH 45083 10/2005)
This fact sheet summarizes information about this chemical and is not a complete
listing of all possible effects. It does not refer to work exposure or emergency
situations.
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