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Smoke - flue gas or colloquially smoke - is a usually by combustion arising aerosol in very finely divided (often colloidal ) form of dust particles ( shining soot , fly ash , unburned matter) and liquid droplets (water, oil fumes, acid vapors, liquid combustion residue) in exhaust gas . In the narrower sense, smoke is a mixture of a solid and a gaseous phase.


The old Germanic word mhd. Rouch , ahd. Rouh belongs to the strong verb smell , ahd. Riohhan , which has no non- Germanic equivalents. The English equivalent smoke , like Schmauch, belongs to the idg. Root smeu-g [h] - "smoking".


Smoke is usually a pollutant for people and the environment. In contrast to an uncontrolled fire ( fire ), controlled combustion usually takes place in closed containers (such as machines , stoves and lamps ) and the smoke gases are discharged in a controlled manner through an appropriate opening ( exhaust , chimney , induced draft ). In industrial systems, the flue gas is cleaned beforehand in order to reduce the proportion of pollutants.


In addition to the formation of open fires and fires, a large part of the flue gases comes from domestic fireplaces such as stoves and boilers that are operated with solid fuels such as wood, wood pellets or coal as well as heating oil .

These flue gases mainly contain solid particles in the form of fly ash , fine dust , soot and the gases water vapor , nitrogen , carbon dioxide , sulfur dioxide , nitrogen oxide and, in the case of incomplete combustion, carbon monoxide or hydrogen .

Flue gases from power plants, blast furnaces, steelworks and other large combustion systems are freed from solids and partially from sulfur dioxide ( flue gas desulphurisation ), nitrogen oxide and hydrogen chloride by means of flue gas cleaning . In the past, they were distributed over a large area through high chimneys so as not to overburden the surrounding area.

Flue gases from motor vehicles are usually referred to as exhaust gases .

Applications and benefits

Regardless of the health and environmental hazards, there are many ways to use smoke, especially when used in a controlled and metered manner.

Craft and technical applications

Enjoyment and culture


Dangers of smoke

Cloud of smoke from a fire in a scrap heap
Even apart from toxins , clouds of smoke harbor a high potential for odor nuisance; Fire in a recycling plant

The smoke poisoning is a common cause of death in residential fires. Death mostly occurs from a combination of thermal injuries with suffocation and lung irritation .

Most fire victims (in Germany 70%) have accidents at night, as a fire can usually be discovered and extinguished quickly during the day. At night, on the other hand, the sense of smell also sleeps , so that the victims are surprised in their sleep without noticing the dangerous combustion gases. That is why almost all fire deaths do not fall victim to the flames, but rather to the poisonous smoke gases that arise during the smoldering fire phase . In Germany, 95% of fire fatalities die as a result of smoke inhalation caused by the odorless gases carbon monoxide and carbon dioxide - even a few lung fillings carbon monoxide are fatal. Smoke detectors can especially during sleep warn potential victims, escape hoods protect to escape through smoke-filled areas.

The emission of large amounts of smoke during volcanic eruptions can have serious consequences for living organisms, agriculture and - as with the eruption of Eyjafjallajökull in 2010 - for air traffic in the affected areas .

Part of smoke is soot , see also diesel soot # Soot formation mechanisms .


Orders from Count Palatine Karl IV. From 1772 also served to prevent a fire in connection with domestic fireplaces. According to the simultaneous building regulations, no more wooden chimneys were allowed to be erected, no more wooden hoses were allowed to be installed, which had to lead the smoke from the fireplace to the fireplace , just as it was forbidden to lead stovepipes out of the window.

Classification in the scheme of chemical substances

Schematic classification of the substances
Pure substance
mixture Mixture of several
Mixture with metallic properties ,
contains at least one metal
Solidliquid ,
gas dissolved  in a liquid
Gaseous bubbles in
a liquid
Rigid foam
Gaseous bubbles in
a solid
Solid particles in
a liquid
Mixture of several
immiscible liquids
mixture of several not
mixable solid
Solid particles
in a gas
Liquid particles
in a gas

See also


  • Karl-Heinz Knorr: Die Roten Hefte, Heft 28 - The dangers of the deployment site . 9th, expanded and revised edition. Kohlhammer, Stuttgart 2018, ISBN 978-3-17-034000-8 .
  • Lothar Schott, Manfred Ritter: Fire Brigade Basic Course FwDV 2 . 20th edition. Wenzel-Verlag, Marburg 2018, ISBN 978-3-88293-220-1 .

Web links

Wiktionary: Rauch  - explanations of meanings, word origins, synonyms, translations
Commons : Rauch  - Album with pictures, videos and audio files

Individual evidence

  1. ^ The dictionary of origin (=  Der Duden in twelve volumes . Volume 7 ). 2nd Edition. Dudenverlag, Mannheim 1989, p. 574, 593 . See also DWDS ( "Rauch" ) and Friedrich Kluge : Etymological dictionary of the German language . 7th edition. Trübner, Strasbourg 1910 ( p. 366 ).
  2. ^ The dictionary of origin (=  Der Duden in twelve volumes . Volume 7 ). 2nd Edition. Dudenverlag, Mannheim 1989, p. 640 . See also DWDS ( "Schmauch" ) and Friedrich Kluge : Etymological dictionary of the German language . 7th edition. Trübner, Strasbourg 1910 ( p. 405 ).
  3. ^ Internet lexicon heating and ventilation technology, entry chimney , Bruno Bosy, in:
  4. See Duden online: fumigate , meaning 1 a and 2.
  5. Fighting voles: How to get rid of pests, see section Poison bait and vole gas .
  6. Cf. Duden online: fumigate , meaning 1 b.
  7. In Switzerland it has been prohibited to smoke the burrows of foxes, badgers and marmots since 2012, see Federal Act on Hunting and the Protection of Wild Mammals and Birds (Hunting Act), Section 7: Penal provisions , Art. 17 h.
  8. ^ Franz-Josef Sehr : The fire extinguishing system in Obertiefenbach from earlier times . In: Yearbook for the Limburg-Weilburg district 1994 . The district committee of the Limburg-Weilburg district, Limburg-Weilburg 1993, p. 151-153 .