What happens when a building suffers moisture damage?

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Citation of this page: Jouko Tuomisto: Arsenic to Zoonoses. Opasnet 2024. [1]. Accessed 22 Dec 2024. This page has also been published elsewhere: 100 kysymystä ympäristöstä ja terveydestä: arsenikista öljyyn. Kustannus Oy Duodecim, Helsinki 2005. ISBN 951-656-221-3.
Upload data {{#opasnet_base_link:Op_en4500}}	Unlike most other pages in Opasnet, the nuggets have predetermined authors, and you cannot freely edit the contents. Note! If you want to protect the nugget you've created from unauthorized editing click here Chapters in the book Arsenic to Zoonoses: Perception of the risks around us Is it the final straw that breaks the camel’s back? Is expert jargon just a way to confuse the man in the street? What is the wisdom in “It’s the dose that determines that a thing is not a poison”? What is a “chemical” after all? Is it more dangerous for us than for our ancestors? Are the risks of the domestic and the workplace environments different? Is man defiled by what goes to his mouth? What is safe to drink? Does water chlorination cause cancer? Are blue-green algae a risk to your life or at least to your liver? Does aluminium cause dementia? Arsenic in the drinking water – reminiscent of the movie “Lavender and old lace”? Are we starting to glow from the uranium in our environment? Fluoride – friend or foe? Blind drunk – or dead drunk? What is really dangerous in our diet? Should we be concerned about the amounts of additives in our diet? May even our cooking habits hurt us? Why not re-freeze thawed out frozen food? The dirty dozen – not just an old movie? Where do the dioxins come from? Are the dioxins the most dangerous chemicals in our environment? Are the PCB compounds really super-poisons? What on earth is PBDE? What are the hormonal disrupters? Tin poisoning – wasn’t even grandma’s copper kitchenware tin-plated? Are heavy metals still a problem today? Is mercury a quicksilver bullet or a slow poison? If this kills insects, what effect is it having on me? The whole field was brown-coloured; should you even go near it let alone eat anything growing there? Should we only eat “organic” products? Isn’t it safe to eat everything that grows naturally? Is it safe to eat wherever it’s convenient? 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Climate change – will it affect our health? Is formaldehyde another type of formalin? Benzene – isn’t it only found in chemistry sets? Can environmental cigarette smoke cause lung cancer? Is there radiation in my home? Do we need to monitor the quality of the air in our homes? How can a building become sick? Do our recreational pastimes require special ventilation systems? Is asbestos still a problem today? What happens when a building suffers moisture damage? Legionnaires’ disease – why should I worry, I’m not in the Foreign Legion? How do air fresheners really work? How to protect our common environment? Why is it worth investing in environmental protection? Indigenous populations live in harmony with their environment, don’t they? Environmental equilibrium and chemicals – impossible or not? Down the drain – is it a case of out of sight, out of mind? Should we compost all our household waste? Does it make sense to burn our domestic waste in power stations? 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Leviticus, the Third Book of Moses in the Old Testament, describes a building that contracts “leprosy” and must be cleaned.^[1] If this does not succeed, it must be dismantled, and the stones and wood taken to a dumpsite. This is still sometimes valid advice. There may be no way to clean a mouldy building which has suffered long-term moisture damage. It has been shown in population studies that moisture damage and mould growth in buildings are associated with respiratory symptoms, general symptoms and increased risk of asthma. The symptoms correlate with the time spent in the building, and tend to ease after termination of the exposure. Sometimes also allergic rhinitis, rheumatoid diseases, sarcoidosis and pneumoconiosis are associated with damp buildings.

Even if the association between the damage and the symptoms has been shown, usually one does not know which factors are responsible for the health effects. Moisture causes chemical disintegration of materials and promotes microbial growth on the surfaces. Both chemical disintegration and microbial growth emit chemical impurities to the air, both volatile organic compounds and semivolatile organic compounds.^[2] Many mould fungi and bacteria produce toxins when they grow on building materials. These may be very toxic.

Moisture damage

Moisture may accumulate in the building because of leaks, through capillary movement of water from the soil, or condensation. Condensation is often due to poor ventilation. It may also be due to wrongly placed non-permeable materials which prevent the escape of humidity out of the wall structures. There are many reasons for moisture problems today: there may be planning mistakes, poor building quality, lack of care and maintenance, and inappropriate use of ventilation systems.

Moisture problems are common. Depending on the definitions of “moisture damage” or “occurrence of mould”, estimates of moisture damage vary from 50 to 80 % and of mould in 5–20 % of buildings. It is difficult to obtain reliable information, because only approximations are possible without opening the wall, floor and roof structures.

The numbers of people exposed to moisture damage and moulds are high, because moisture damage can occur in dwellings, schools, day-care centres, workplaces, hospitals and recreational sites. Since there is no exact information on how extensive and long-lasting the moisture damage has to be to cause health problems, we have to be satisfied with a conservative approximation on the number of exposed people. Probably at least every third person will have contact with some sort of moisture or mould damaged indoor environment. Studies on teachers have suggested that exposure to microbes is higher than one could estimate on the basis of microbe concentrations in the workplaces or at home. This is mainly because people’s own activities cause resuspension of dust, called the “personal cloud”.

Release of chemicals in moisture damage

Moisture damage may cause different disintegration processes in building materials. This produces various chemicals being released into the indoor air. An example is alkaline disintegration of a plastic floor surface, if the surface was installed on a concrete surface which was not yet dry. The process may continue even after moisture is no longer present. The smell of ammonium is a sign of this sort of a problem. In some instances, the moisture comes from the soil below the building.

Release of microbial products to indoor air

Microbial growth releases particulate matter and volatile compounds which often are recognized as the musty smell of a mouldy cellar. Particles can be spores or cells (0.001 to 0.05 mm) or finer particles (0.000,01 to 0.000,1 mm), and they may contain allergens or toxic intermediates. When microbes are growing on surfaces, the release can vary depending on air flows and ambient conditions.

Volatile metabolites released by microbes may be hydrocarbons, acids, alcohols or other organic compounds just like other volatile organic compounds in indoor air. Attempts to identify compounds specific to microbial metabolism have not usually been successful, because there may be other sources such as outdoor air. Even if it is easy to recognise the typical smell of a humid cellar, the chemical characterization of the smell is difficult because of the low concentrations and the huge variety of chemicals present.

Also microbial toxins are products of fungal or bacterial metabolism. These products are usually not volatile, but they are bound to particles such as spores. Moulds producing toxins when growing on construction materials include Stachybothrus chartarum, Aspergillus versicolor and several other species of Aspergillus, and many species of Trichoderma, Fusarium, Chaetomium, and Penicillium families. These species are common in moisture damaged construction materials. There can also be some toxin producing bacterial species found e.g. Bacillus and Nocardiopsis families.

Exposure to microbial toxins via indoor air has not been studied very extensively. This is in contrast to the thorough studies of toxins in food. It is in part due to methodological difficulties, because the concentrations are usually very low, and the number of compounds may be high. Microbial toxins may be irritating, influence the immune and nervous systems, and cause cancer. In animal husbandry, many effects of microbial toxins have been described.

There is little solid information on the effects of low concentrations of microbial toxins in indoor air on humans. It is obvious that the symptoms and diseases attributable to these toxins are too rare to be detected in epidemiological population studies. However, in individual cases, this is one of the most important aspects of indoor exposures.

Indoor moisture problems are as yet poorly characterized. Moisture problems are common; what is not well understood is why sometimes these are associated with health problems and sometimes not.

Notes and references

↑ Levitictus 14:34-57
↑ See the chapter "Do we need to monitor the quality of the air in our homes?"

One level up: The air that we breathe

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[1] Levitictus 14:34-57

[2] See the chapter "Do we need to monitor the quality of the air in our homes?"

[1]

[2]

What happens when a building suffers moisture damage?

Moisture damage

Release of chemicals in moisture damage

Release of microbial products to indoor air

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