What is Sulfur
Dioxide?
Sulfur Dioxide (SO2) is a colorless, reactive gas. It is produced when
sulfur-containing fuels such as coal and oil are burned, during the smelting of
metal, and by other industrial processes. It can also enter the
atmosphere naturally when volcanos erupt, and as sulfate particles from
ocean spray. Generally, the highest concentrations of SO2 are found near
large industrial sources. High concentrations of this pollutant are not usually found in the United States.
SO2 causes rain to become acidic, and it reduces visibility by creating haze (smog).
The Environmental Protection Agency uses its Air Quality
Index to provide general information to the public about air quality
and associated health effects. An Air Quality Index (AQI) of 100 for any
pollutant corresponds to the level needed to violate the federal health
standard for that pollutant. For sulfur dioxide, an AQI of 100 corresponds to 0.14
parts per million (ppm) over a 24-hour period -- the current federal
standard.
People with asthma should
consider limiting outdoor exertion.
151 - 200
Unhealthy
Children,
asthmatics, and people with heart or lung disease
should limit outdoor
exertion.
201 - 300
Very Unhealthy
Children,
asthmatics, and people with heart or lung disease
should avoid outdoor
exertion; everyone else should limit outdoor
exertion.
301
- 500
Hazardous
Children,
asthmatics, and people with heart or lung disease
should remain indoors;
everyone else should avoid outdoor
exertion.
What are the health effects from Sulfur Dioxide?
Children and adults with asthma who are active outdoors are most
vulnerable to the health effects of SO2. The primary effect they
experience, even with a brief exposure, is a narrowing of the airways,
which may cause symptoms such as wheezing, chest tightness, and shortness
of breath. Symptoms increase as SO2 concentrations and/or breathing rates
increase. When exposure ceases, lung function typically returns to normal
within an hour.
At very high concentrations, SO2 may cause wheezing, chest tightness,
and shortness of breath in people who do not have asthma.
Long-term exposure to both SO2 and fine particles can cause
respiratory illness, alter the lung's defense mechanisms, and aggravate
existing cardiovascular disease. People who may be most susceptible to
these effects include individuals with cardiovascular disease or chronic
lung disease, as well as children and the elderly.
