What is sulfur dioxide

Sulfur dioxideAuxiliary materialsPreservative sulfur dioxide (SO2) is a colorless gas with a pungent odor that is produced when sulfur is burned. In nature, for example, it is released from volcanoes. Sulfur dioxide has antimicrobial and preservative properties and is used, among other things, for the synthesis of sulfuric acid, as a preservative for food and for chemical syntheses. Sulfur dioxide is highly toxic and inflammatory. It is also released into the air when fossil fuels are burned because they contain relatively high levels of sulfur. Worldwide shipping is responsible for a high proportion of emissions.

synonym: SO2, E 220, Sulfur dioxide, Sulfur dioxide


Sulfur dioxide is commercially available as a liquefied gas in pressurized gas cylinders.

Structure and properties

Sulfur dioxide (SO2, 64.1 g / mol) is a colorless gas with a characteristic, pungent and irritating sulfur odor, which is soluble in water. The boiling point is -10 ° C. Sulfur dioxide is not flammable and is heavier than air. It is created when sulfur is burned. This reaction is exothermic:

Sulfur dioxide occurs naturally, for example, in volcanic gases and in low concentrations in the earth's atmosphere.

Sulfur dioxide is used for the synthesis of sulfuric acid:

The extremely unstable sulphurous acid is formed with water, but this cannot be detected in the water:

Sulfur dioxide. The angle between the oxygen atoms is 119 °. Click to enlarge. Illustration © PharmaWiki.


Sulfur dioxide has antiseptic, antimicrobial, insecticidal, preservative, bleaching (decolorizing) and antioxidant properties. It is also harmful to many plants and animals in higher concentrations.

Sulfur dioxide is formed in the human body from the amino acid cysteine, for example, and performs physiological functions.

application areas

The areas of application include (selection):

unwanted effects

When inhaled, sulfur dioxide is toxic and highly inflammatory. It causes severe burns to the skin, can irritate the respiratory tract, and cause serious eye damage. The corresponding precautionary measures in the safety data sheet must be observed.

Sulfur dioxide is released when fossil fuels are burned because it contains sulfur in a relatively high concentration. This is particularly problematic if the sulfur is not removed before combustion. Worldwide shipping, including cruise ships, is responsible for a high contribution to emissions.

Sulfur dioxide can promote the development of respiratory diseases and have a negative influence on the course of the disease.

see also

Sulfur, sulfuric acid, sulphurous acid, burns chemistry, sulfites

  • EFSA
  • Specialist literature
  • Huang Y. et al. Endogenous Sulfur Dioxide: A New Member of Gasotransmitter Family in the Cardiovascular System. Oxid Med Cell Longev, 2016, 2016, 8961951 Pubmed
  • Kochi T. et al. Influence of sulfur dioxide on the respiratory system of Miyakejima adult residents 6 years after returning to the island. J Occup Health, 2017, 59 (4), 313-326 Pubmed
  • Chemistry textbooks
  • Encyclopedias of food technology
  • Pharmacy Lexicons
  • Lung League Switzerland
  • Safety data sheet (CH)
  • Wang X.B. et al. Sulfur dioxide: foe or friend for life? Histol Histopathol, 2017, 32 (12), 1231-1238 Pubmed
  • Wang X.B., Du J.B., Cui H. Sulfur dioxide, a double-faced molecule in mammals. Life Sci, 2014, 98 (2), 63-7 Pubmed

Conflicts of Interest: None / Independent. The author has no relationships with the manufacturers and is not involved in the sale of the products mentioned.

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This article was last changed on 10/31/2020.
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