All moulds have the potential to cause health effects. Moulds produce allergens, irritants and in some cases, toxins that may cause reactions in humans. The types and severity of symptoms depend, in part, on the types of mould present, the extent of an individual's exposure, the ages of the individuals and their existing sensitivities or allergies.
Allergy-like symptoms such as eye, nose, throat, headache, fatigue and dizziness can result from exposure to these microbiological contaminants. Chronic exposure can lead to Hypersensitivity pneumonitis, allergic asthma and chronic allergy symptoms. Some species of mould produce toxic substances called Mycotoxins and release them into the environment. Many of these Mycotoxins are neurotoxins or immuno-suppressors. Mycotoxins can cause adverse health effects at very low concentrations. Some of the moulds that are known to produce mycotoxins are commonly found in moisture damaged building materials. Exposure pathways include inhalation, ingestion and skin contact.
Several moulds also release Microbial Volatile Organic Compounds into the air. These volatile carbon/oxygen based gases are emitted as part of the microbial metabolism and produce the odour associated with the presence of mould in the home. MVOCs are known irritants. Exposure to MVOCs from mould has been linked to headaches, nasal irritation, dizziness, fatigue and nausea.
Allergic reactions to mould are common and can be set off by breathing spores or skin contact to mould when the person has an increased level of sensitivity. Reactions my be immediate or delayed and may include fever, sneezing, runny nose and/or burning eyes. It has been reported that repeated or even a single exposure to mould may cause a previously non-sensitive individual to become sensitive. The more prolonged the exposure, the greater the risk of developing sensitivity.
Asthma attacks have been triggered by mould exposure. The irritants produced by moulds may also worsen asthma in non-allergic (non-sensitized) people.
A disease that resembles pneumonia called Hypersensitivity Pneumonitis may develop during either a short, acute exposure or chronic exposure. This is a rare disease and very debilitating.
Persons with compromised immune systems may fall prey to opportunistic infections as a result of their bodies' inability to protect itself against common mould exposure.
Moist indoor environments also lead to rapid and continuous growth of bacteria. Many bacteria are known to cause diseases. Although non-pathogenic bacteria do not cause disease, they can challenge the immune system when inhaled in large doses. Non-Pathogenic bacteria can become opportunistic pathogens (disease-causing) on cancer patients or others with compromised immune systems. Negative gram bacteria produce Endotoxins, which can cause fever, headaches, chills, impaired organ function, shock and respiratory distress.
High humidity, condensation and moisture damaged building materials create an environment which supports the rapid and continuous growth of moulds, mildews and bacteria in the home. The recommended "Comfort Zone" for relative humidity in the home is 40% RH to 60% RH. Deviations from this range can coincide with increased levels of bacteria, viruses, mould and other factors that reduce air quality and lead to respiratory problems, including sinus problems and asthma. Some indoor air quality specialists recommend that relative humidity be maintained at less than 55% to control fungal proliferation.
Excess moisture in the home is also a problem because it leads to decay of building materials; it creates conditions that support wood-destroying insect infestations and supports dust mite activity, which in turn can contribute to allergies and asthma. (Dust mites require humidity of over 60% to thrive. Populations are wiped out when humidity levels are below 50%.)
(from www.myoasis.ca )