What Is SO2?
Sulfur dioxide (SO₂) is a significant air pollutant formed when sulfur-containing fuels—like coal, petroleum oil, or diesel—are burned. It consists of sulfur and oxygen and is known for its sharp, irritating odor. SO₂ emissions can undergo chemical transformations in the atmosphere, forming sulfate particles, a major contributor to fine particle pollution (PM₂.₅). These fine particles are harmful to respiratory health and can be carried over large distances by wind, spreading their impact far beyond their original source. This transport of sulfate particles contributes to regional air quality issues and can affect communities hundreds of miles away from emission sources.
Where does SO2 Come From?
The main sources of SO₂ emissions are power plants, commercial and institutional boilers, internal combustion engines, and industrial processes like petroleum refining and metal processing. Other contributors include diesel engines in older buses, trucks, locomotives, ships, and off-road equipment, such as construction vehicles.
Who Is at Risk from SO2 exposure?
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Individuals who are pregnant;
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Infants, children and teens;
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Older adults (>65 years of age);
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People with pre-existing medical conditions such as asthma, chronic obstructive pulmonary disease (COPD), cardiovascular disease, diabetes, lung cancer
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Current or former smokers;
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People with low socioeconomic status; and
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People of color.
How SO2 Harms Your Health?
Sulfur dioxide (SO₂) exposure poses several health risks, particularly to the respiratory system:
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Wheezing, shortness of breath, and chest tightness: SO₂ can trigger these symptoms, especially during physical activities like exercise, where rapid breathing allows more of the gas to reach the lower respiratory tract. Breathing through the mouth also increases SO₂ intake.
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Long-term exposure effects: Prolonged exposure to high levels of SO₂ can worsen respiratory symptoms and reduce lung function over time.
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Asthma-related breathing difficulties: Even brief exposure to high SO₂ levels can cause breathing difficulties for people with asthma, particularly when they are active outdoors.
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Increased hospital visits: SO₂ exposure heightens the risk of emergency room visits and hospital admissions, especially for vulnerable groups, including children, older adults, and those with asthma.