Sulfur Dioxide (SO2)
A pungent gas released by burning sulfur-containing fossil fuels, primarily from power plants and industrial facilities.
Detailed Explanation
Sulfur dioxide is produced primarily by the combustion of sulfur-containing fossil fuels, especially coal and oil, in power plants and industrial processes such as metal smelting and petroleum refining. It is a sharp-smelling gas that can irritate the nose, throat, and airways. Even brief exposure to elevated SO2 levels can cause bronchoconstriction — a tightening of the muscles around the airways — which is particularly dangerous for people with asthma. SO2 also reacts with other compounds in the atmosphere to form fine particulate matter (PM2.5) and contributes to acid rain, which damages ecosystems, buildings, and water quality. SO2 emissions in the United States have declined dramatically over the past several decades, falling by more than 90% since 1980, primarily due to the Clean Air Act's acid rain program and the shift from coal to natural gas and renewable energy in electricity generation. The EPA's current 1-hour standard for SO2 is 75 parts per billion. While SO2 is rarely the dominant pollutant in most US cities today, industrial areas and regions near coal-fired power plants may still experience elevated levels. AirHistory tracks SO2 as part of pollutant breakdowns for each city.
Related Terms
Acid Rain
Precipitation made acidic by sulfur dioxide and nitrogen oxide emissions, which damages ecosystems, buildings, and water quality.
Criteria Pollutants
The six common air pollutants regulated by the EPA under the Clean Air Act: ozone, PM2.5, PM10, CO, NO2, and SO2.
Clean Air Act
The primary federal law governing air quality in the United States, first enacted in 1963 and significantly amended in 1970 and 1990.
Emissions Inventory
A comprehensive accounting of air pollutant emissions from all sources in a geographic area, used for regulation and planning.
Frequently Asked Questions
A pungent gas released by burning sulfur-containing fossil fuels, primarily from power plants and industrial facilities.
Sulfur dioxide is produced primarily by the combustion of sulfur-containing fossil fuels, especially coal and oil, in power plants and industrial processes such as metal smelting and petroleum refining. It is a sharp-smelling gas that can irritate the nose, throat, and airways. Even brief exposure to elevated SO2 levels can cause bronchoconstriction — a tightening of the muscles around the airways — which is particularly dangerous for people with asthma.