What is mold


What are molds?

With Mold is not an exact genus of fungi, but is colloquially summarized as all those fungi that form a rapidly growing and visible thread network (mycelium) on infected surfaces. Characteristic is a fluffy or dusty coating, which can appear from white, gray to deep black or yellow, green, blue to bright red. Fungi conquered a large ecological niche, so that biology assigns them the 3rd realm, between that of bacteria and plants.

They are typically found on spoiled food (e.g. bread, fruit, milk products), damp wood or walls. Moisture is the prerequisite for mold to spread. Molds break down organic material and prove to be recycling specialists, as fungi can break down even things that are difficult for bacteria to digest, such as vegetable cellulose, or the lignin contained in wood with the help of their enzymes.

Molds are mostly composed of the Ascomycetes (hose fungi) and Zygomycetes (yoke fungi) families. More precisely, however, from their so-called asexual manifestations, the so-called Deuteromycetes (earlier than fungi inperfekti designated) together. Well-known representatives are Mucor species (head mold), Aspergillus species (watering can mold), Penicilien species (pincer mold) or the types of mold which form a dark mycelium and are also often summarized in the group of Dematiaceae (black fungi). Unfortunately, the classification and taxonomic allocation of the individual mushrooms is more than confusing, because they have grown historically and are not systematically shaped, so that one speaks of the "mycological confusion of language". In addition, the assignments of some fungi are changing due to the current possibilities of DNA analysis and the taxonomic classification in microbiology is in a phase of reorientation. The reader should not be confused by this, however, as this is of subordinate importance for the fundamental consideration of the problem of mold infestation in buildings and the assessment of the individual species can confidently be left to the specialist.

Health risks from mold?

When considering the health risk posed by mold, one must first consider the consequences of mold infestation.

Depending on the species, molds can have an allergenic effect due to their spores and, in extreme cases, cause infections (colonization of the human body) in people with a disturbed immune system, or the cell wall components are able to trigger inflammatory processes. Under certain conditions, some molds form mycotoxins (fungus toxins), which can cause intoxication, especially if improper renovation work is carried out. A mold infestation often leads to serious and long-lasting odor problems due to the volatile metabolic products (MVOC) of the fungi.

It should be taken into account that not only molds grow on moist materials, but also bacteria, quasi the competitors of the molds, which also represent a health risk for the residents. In colloquial terms, however, there is usually no differentiation and therefore instead of being inconveniently affected by bacteria and fungi or microbial infestation, it is referred to as mold infestation.

In the scientific literature, the most varied and unfortunately unspecific symptoms are listed for residents as a result of mold infestation. However, one should be careful with information about the allocation of specific health risks to individual molds, since a possible toxic or allergenic potential of a mold species is different depending on the growth phase, genetic predisposition or the environmental conditions.

Epidemiological studies show that there is a connection between damp apartments, mold infestation and a specific health risk for the residents. It does not matter whether the mold infestation is visible (e.g. on the wall surface) or hidden (behind furniture or in components) or even not visible to the naked eye.

On the other hand, there is no direct connection between a certain concentration of spores of a type of mold in the room air and a direct health risk for the respective resident. Although individual types of fungus can be described as possible mycotoxin producers, with an allergic potential or even with a potential risk of infection, mycotoxins are only formed under certain conditions, not every immune system reacts in the same way to potentially allergenic fungal spores and a healthy immune system successfully fends off a fungal attack from.

As a result, no general limit values ​​for molds in the room air can be derived, since it is also not possible to determine with certainty which concentration still represents a harmless dose for the individual. The WHO guidelines on indoor air quality and the Federal Environment Agency therefore draw the same conclusion that extensive fungal infestation in a building generally represents a possible health risk for residents. Indoor air examinations are therefore primarily used to obtain information on a hidden invisible infestation or to ensure that mold remediation has been successful. Since the mechanism of action is not exactly known, the focus should not be on avoiding indoor air pollution, but rather on recognizing and eliminating the mold infestation itself.

Basics for the remediation of a mold infestation

Since the health mechanisms of a mold infestation on the residents are not known in detail, the sole aim of the renovation should not be to avoid indoor air pollution by mold spores. The goal of a renovation, on the other hand, must be to focus on the (mechanical) removal of the mold infestation itself.

General recommendations for avoiding mold infestation can be found in abundance. However, they prove to be of little help in specific individual cases. Avoiding or eliminating mold growth means first and foremost avoiding or eliminating moisture. The use of commercially available disinfectants or mold removers (biocides) is therefore not promising, but rather counterproductive. On the one hand, the biocides pollute the interior again; on the other hand, the fungi are able to use organic biocides themselves again as a source of nutrients through an adapted enzyme spectrum. Chemical treatment of mold infestation also has no discernible benefit in terms of preventive health care. The allergic potential is neither reduced nor successfully eliminated the mycotoxins or odors that may be present. As a result, the remediation should not focus on mold control, but on removal of the mold infestation.

The only successful and simple strategy is to completely remove the mold-infested material. This should be done properly without the release and spread of spores or other fungal constituents. Basically, in the case of an extensive infestation, the layperson is usually overwhelmed and needs professional assistance. It should also be mentioned that the legislator and the employers' liability insurance association have issued clear ordinances and rules for dealing with mold and that dealing with mold is not, as is often assumed, in a legally free area.

What advice can you give to those affected?

In their search for a solution to the problem, those affected will be confronted with many opposing pieces of advice, which can be shaped by different interests. For example, the expert from the responsible building insurance company primarily regards moisture damage and mold, on the other hand, as secondary consequences without any additional need for regulation. Here, those affected should obtain independent expertise from a building biologist who has comprehensible experience with the task at hand. Because the causes of mold infestation are as individual as their solutions.

More information

Further reading worth reading, ... which document the current state of knowledge well (also for the layman) free of charge at: www.umweltbundesamt.de

  • Advice: Help! Mold in the house
  • Guide to preventing, investigating, evaluating, and remedying indoor mold growth
  • Guide to the search for causes and remediation of mold growth indoors ("Mold remediation guide")

Professional, independent help:

List of companies that carry out mold remediation:

Source - author

See also