Mold smell - what measures should be taken?

Mold odors are extremely unpleasant. Where you come from, how mold can smell, and what you should do in the case of mold odors, and what hints he gives, tells you in detail this article on the subject.

mildew odors

Mold can smell very different, depending on the type of mold and its background, which it has attacked. In general, mildew odors can have the following odor notes:

  • earthy
  • moldy
  • Smell of forest (soil)
  • Smell of musty cellar
  • only slightly musty smell

Odors in the mold

Depending on the mold, different odors can be released by mold fungi. These odors are called MVOCs. The abbreviation stands for volatile, microbial hydrocarbons. Depending on their metabolism, the molds release these substances into the room air, where they become perceptible as an odor. In other cases, a special gas, the so-called geosmin, is ejected, which in high concentrations is also perceptible to humans.

Chemical properties of the odors

Although the odors are assigned to a class, they are not chemically identical. Some odorous substances have the character of solvents, as they are also used technically. These substances can cause even unpleasant symptoms in humans in very high concentrations:

  • a headache
  • difficulty breathing
  • reddened, watery eyes
  • Concentration and sleep disorders

However, this is only rarely the case, and only if the concentrations of these substances in the indoor air are particularly high.

Typical concentrations of odorants

Low concentrations

Little or only selective mold in the room often releases only a few nanograms of odorous substances in the room. This amount is too small to be perceived by humans, but it is perceptible to dogs. Therefore, so-called "mold detection dogs" are usually used together with a specialist in the mold search. Mold that releases such small amounts of odorants is usually not visible either.

High concentrations

While some 100 ng (nanograms) per cubic meter of room air are common with "normal" mold in the house, in rare cases higher concentrations can occur. Above all, solvent MVOCs form such high concentrations of 1 μg (1,000 ng) and more. From a concentration of around 500 μg / m³, such substances alone are considered hazardous to health (unless there are other toxic substances, such as the mycotoxins of the Aspergillus flavus, the yellow mold).


Even with small signs of moldy odors, you should immediately search for the cause. Mold infestation does not always have to be immediately visible - in case of doubt you should have a mold test done at the pharmacy or by a professional company, possibly also with a gray dog. Under no circumstances should it be left to the mere "Übertünchen" of the mold smell with air fresheners or the like. Always take mold very seriously!

Tips & Tricks

Better than a so-called rapid mold test is a test by a certified testing laboratory. During the test, it is often possible to determine the type (and therefore the individual risk) of the mold load.

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