ACSA Affiliate Content

EPA Air Quality

The Association of California School Administrators is the largest umbrella organization for school leaders in the United States, serving more than 17,000 California educators.

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Air Quality Index suLFur dIoxIde What is sulfur dioxide? Sulfur dioxide, a colorless, reactive gas, is produced when sulfur-containing fuels such as coal and oil are burned. Generally, the highest levels of sulfur dioxide are found near large industrial complexes. Major sources include power plants, refineries, and industrial boilers. What are the health effects and who is most at risk? Sulfur dioxide is an irritant gas that is removed by the nasal passages. Moderate activity levels that trigger mouth breath- ing, such as a brisk walk, are needed for sulfur dioxide to cause health effects in most people. • People with asthma who are physically active outdoors are most likely to experience the health effects of sulfur dioxide. e main effect, even with very brief exposure (minutes), is a narrowing of the airways (called bron- choconstriction). is may be accompanied by wheez- ing, chest tightness, and shortness of breath, which may require use of medication that opens the airways. Symptoms increase as sulfur dioxide levels or breathing rate increases. When exposure to sulfur dioxide ceases, lung function typically returns to normal within an hour, even without medication. • At very high levels, sulfur dioxide may cause wheezing, chest tightness, and shortness of breath even in healthy people who do not have asthma. • Long-term exposure to sulfur dioxide may cause respira- tory symptoms and illness, and aggravate asthma. People with asthma are the most susceptible to sulfur dioxide. However, people with other chronic lung diseases or car- diovascular disease, as well as children and older adults, may also be susceptible to these effects. How can I protect my health at different AQI values? * An AQI of 100 for sulfur dioxide corresponds to a level of 75 parts per bil- lion (averaged over one hour). AQI Value Actions to Protect Your Health From sulfur dioxide Good (0–50) None Moderate (51–100*) None Unhealthy for Sensitive Groups (101–150) People with asthma should consider reducing exertion outdoors. Unhealthy (151–200) Children, asthmatics, and people with heart or lung disease should reduce exertion outdoors. Very Unhealthy (201–300) Children, asthmatics, and people with heart or lung disease should avoid outdoor exertion. Everyone else should reduce exertion outdoors. Children and adults with asthma who are active outdoors are most vulnerable to the health effects of sulfur dioxide. 10

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