Mold Inspections
What is Mold?
Molds include all species of microscopic fungi that grow in the form of multicellular filaments, called hyphae. In contrast, microscopic fungi that grow as single cells are called yeasts. A connected network of these tubular branching hyphae has multiple, genetically identical nuclei and is considered a single organism, referred to as a colony or in more technical terms a mycelium.
There are thousands of known species of molds, which include opportunistic pathogens, saprotrophs, aquatic species, calders and thermophiles. Like all fungi, molds derive energy not through photosynthesis but from the organic matter, inside of which they live.
The biological study of molds shows they reproduce through small spores, which may contain a single nucleus or be multinucleate. Mold spores can be asexual or sexual many species can produce both types. Some can remain airborne indefinitely, and many are able to survive extremes of temperature and pressure.
Although molds grow on dead organic matter everywhere in nature, their presence is only visible to the unaided eye when mold colonies grow. A mold colony does not comprise discrete organisms, but an interconnected network of hyphae called a mycelium. Nutrients and in some cases organelles may be transported throughout the mycelium. In artificial environments like buildings, humidity and temperature are often stable enough to foster the growth of mold colonies, commonly seen as a downy or furry coating growing on food or other surfaces.
Some molds can begin growing at temperatures as low as 2°C. When conditions do not enable growth, molds may remain alive in a dormant state, within a large range of temperatures before they die. The many different mold species vary enormously in their tolerance to temperature and humidity extremes. Certain molds can survive harsh conditions such as the snow-covered soils of Antarctica, refrigeration, highly acidic solvents, and even petroleum products such as jet fuel.
Health
Molds are everywhere in nature, and mold spores are a common component of household and workplace dust. However, when mold spores are present in large quantities, they can present a health hazard to humans, potentially causing allergic reactions and respiratory problems.
Some molds also produce mycotoxins that can pose serious health risks to humans and animals. Exposure to high levels of mycotoxins can lead to neurological problems and in some cases death. Prolonged exposure, e.g. daily workplace exposure, can be particularly harmful. The term toxic mold refers to molds that produce mycotoxins, and not to all molds in general.
Mold in buildings and homes
Mold growth in buildings can lead to a variety of health issues. Various practices can be followed to mitigate mold issues in buildings, the most important of which is to reduce moisture levels that can facilitate mold growth. Removal of affected materials after the source of moisture has been reduced and/or eliminated may be necessary for remediation. Mold assessment and mold remediation are techniques used in occupational health.
Mold assessment is the process of identifying the location and extent of the mold hazard in a structure. Mold remediation is the process of removal and/or cleanup of mold from an indoor environment.
It has been estimated that 40 percent of United States homes have some form of mold problem. (source: Niemeier, R. Todd, Sivasubramani, Satheesh K., Reponen, Tiina and Grinshpun, Sergey A., (2006) "Assessment of Fungal Contamination in Moldy Homes: Comparison of Different Methods", Journal of Occupational and Environmental Hygiene)
Growing Conditions and Causes
Molds and fungi are found everywhere inside and outside, and can grow on almost any substance when moisture is present. Molds when they reproduce make spores, which can be carried by air currents. When these spores land on a moist surface that is suitable for life, they begin to grow. Molds are essential to the natural breakdown of organic materials in the environment. Mold is normally found indoors at levels that do not affect most healthy individuals. When these levels become abnormally high as determined by indoor air quality testing or a mold inspection, remediation is recommended to be carried out by a professional remediation company.
Because common building materials are capable of sustaining mold growth, and mold spores are everywhere, mold growth in an indoor environment is typically related to an indoor water or moisture problem. Another common source of mold growth is flooding.
For significant mold growth to occur, there must be a source of water (which could be invisible humidity), a source of food, and a substrate capable of sustaining growth. Common building materials, such as plywood, drywall, furring strips, carpets, and carpet padding are food for molds. In carpet, invisible dust and cellulose are the food sources (see also dust mites). After a single incident of water damage occurs in a building, molds grow inside walls and then become dormant until a subsequent incident of high humidity; this illustrates how mold can appear to be a sudden problem, long after a previous flood or water incident that did not produce a mold-related problem. The right conditions re-activate mold.
Spores need three things to grow into mold: nutrients, moisture, and time.
Food sources for molds in buildings include cellulose-based materials, such as wood, cardboard, and the paper facing on both sides of drywall, and all other kinds of organic matter, such as soap, dust and fabrics. Carpet contains dust made of organic matter such as skin cells. If a house has mold, the moisture may be from the basement or crawl space, a leaking roof, or a leak in plumbing pipes behind the walls. Insufficient ventilation can further enable moisture build-up. The more people in a space, the more humidity builds up. This is from normal breathing and perspiring. Visible mold colonies may form where ventilation is poorest, and on perimeter walls, because they are coolest, thus closest to the dew point.
If there are mold problems in a house only during certain times of the year, then it is probably either too air-tight, or too drafty. Mold problems occur in airtight homes more frequently in the warmer months (when humidity reaches high levels inside the house, and moisture is trapped), and occur in drafty homes more frequently in the colder months (when warm air escapes from the living area into unconditioned space, and condenses). If a house is artificially humidified during the winter, this can create conditions favorable to mold. Moving air may prevent mold from growing since it has the same desiccating effect as lowering humidity. Keeping indoor air temperature higher than 74 °F (23.3 °C) also has an inhibiting effect on mold growth.
Questions?
We hope this information has provided you information you need to understand what mold is, how it grows and how it can affect your life. Please call DANWAY INSPECTION GROUP today if you have any questions about mold, mold assessments and mold remediation.