What Is Sulfur Dioxide?
ATSDR describes sulfur dioxide as a colorless gas with a pungent odor that becomes a liquid under pressure and dissolves in water very easily. The EPA says the largest source in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities, with smaller sources including extracting metal from ore, volcanoes, and locomotives, ships and other vehicles and heavy equipment that burn high-sulfur fuel.
The EPA says short-term exposures to sulfur dioxide can harm the human respiratory system and make breathing difficult. ATSDR says exposure occurs from breathing it in air, that it affects the lungs, and that high levels may result in burning of the nose and throat, breathing difficulties and severe airway obstructions.
There are limits in air and in food. The EPA's primary national ambient air quality standard for sulfur dioxide, established in 2010, is 75 parts per billion based on the 3-year average of the 99th percentile of yearly 1-hour daily maximum concentrations. In food, 21 CFR 182.3862 lists sulfur dioxide as generally recognized as safe when used in accordance with good manufacturing practice, except that it is not used in meats, in food recognized as a source of vitamin B1, or on fruits or vegetables meant to be served or sold raw or presented as fresh.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Government sourceATSDR describes sulfur dioxide as a colorless gas with a pungent odor that is a liquid under pressure and dissolves in water very easily. ATSDR, CDC ↗
- Government sourceThe EPA says the largest source of sulfur dioxide in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. US EPA ↗
- Government sourceThe EPA says short-term exposures to sulfur dioxide can harm the human respiratory system and make breathing difficult. US EPA ↗
- Government sourceATSDR says sulfur dioxide affects the lungs and at high levels may result in burning of the nose and throat, breathing difficulties and severe airway obstructions. ATSDR, CDC ↗
- Regulatory filingThe EPA says its primary air quality standard for sulfur dioxide, established in 2010, is 75 parts per billion based on the 3-year average of the 99th percentile of yearly 1-hour daily maximum concentrations. US EPA ↗
- Regulatory filingUnder 21 CFR 182.3862, sulfur dioxide is generally recognized as safe under good manufacturing practice, except in meats, in foods recognized as a source of vitamin B1, or on produce sold or served raw or presented as fresh. US FDA, 21 CFR 182.3862 (eCFR) ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.