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Pollutants

Sulfur Dioxide (SO2) - 1 Hour Standard

National Ambient Air Quality Standard – 75 parts per billion (ppb) - Based on a 99th percentile, averaged over 3 years.


Sulfur dioxide (SO2), a colorless, reactive gas, is produced when sulfur-containing fuels such as coal and oil are burned. Major sources include power plants and industrial boilers. Generally, the highest levels of sulfur dioxide are near large industrial complexes.

Air Quality Index (AQI): Sulfur Dioxide (SO2)

Index Values

Levels of Health Concern

Cautionary Statements

0-50

Good

None

51-100*

Moderate

None

101-150

Unhealthy for
Sensitive Groups

People with asthma should consider reducing exertion outdoors.

151-200

Unhealthy

Children, asthmatics, and people with heart or lung disease should reduce exertion outdoors.

201-300

Very Unhealthy

Children, asthmatics, and people with heart or lung disease should avoid outdoor exertion. Everyone else should reduce exertion outdoors.

301-500

Hazardous

Children, asthmatics, and people with heart or lung disease should remain indoors. Everyone else should avoid exertion outdoors.

* An AQI of 100 for sulfur dioxide corresponds to an SO2 level of 75 ppb (averaged over 1 hour).