For over two decades, mold has remained in the news.
People are talking about the effect on population health and damage to the building. But what are the risks and issues?
The available science on molds and their potential health effects remains under study, but considerable progress has been made. The US Centers for Disease Control and Prevention (CDC), the Institute of Medicine of the US National Academy of Sciences, the World Health Organization, and Health Canada all agree that living or working in a building with mold damage results in increased risk of respiratory disease. Although there are several guidance documents available, there are no accepted national or international standards for mold investigation, evaluation or remediation.
Media attention on this topic often creates emotionally charged circumstances, making scientific and professional judgment, as well as reasoned dialogue on this subject, very difficult. In some instances, building owners have been known to ignore or dismiss potentially serious problems. Importantly, many indoor air quality (IAQ) problems have nothing to do with mold, and buildings seldom have only one indoor environmental quality problem. It is essential to consider multiple sources of building IAQ problems instead of focusing on just mold concerns. In other instances, building occupants or public officials armed with mold sampling reports of dubious quality have reacted with alarm to potential threats, making risk communication very difficult.
The Facts about Mold:
What is mold? The term “mold” is a colloquial term for a group of filamentous fungi that are common on food or wet materials. This includes the green Penicillium species that produces penicillin, and fungi that spoil our bread, fruit, cheese and crops. Most of these are Ascomycetes that produce a lot of spores. There are thousands of species of mold and they can be any color. Different mold species are adapted to different moisture conditions ranging from very wet to just damp. Many times, mold can be detected by a musty odor. Live spores act like seeds, forming new mold growths (colonies) under the right conditions.
How does mold get into a house or building? Mold and fungal spores occur naturally outdoors, where fungi are the earth’s most important recyclers. Indoors, mold needs moisture to grow; it becomes a problem only where there is water damage, elevated and prolonged humidity, or dampness. Common sources of excessive indoor moisture that can lead to mold problems include:
· · flooding from surface waters (i.e., overflowing rivers) or from severe storms;
· · roof leaks from damaged or missing roofing materials, ice dams or blocked gutters;
· · storm‐driven rain through window frames, exterior walls or door assemblies;
· · leaking pipes, sewer back‐ups or overflows;
· · damp basements or crawl spaces due to a high water table (rising damp) or poorly managed
rainwater drainage; and
· · condensation on cold surfaces.
How can I prevent mold growth? The key to preventing and stopping indoor mold growth is to control excessive moisture and condensation. Keeping susceptible areas in the home clean and dry is critical. In general, mold will not grow indoors without water, dampness or excessive moisture.
There are three main factors that contribute to condensation of water on building surfaces:
· · Relative Humidity: Condensation occurs when the air is saturated with water and it cannot hold any more moisture. For example, steam generated from bathroom showers or from cooking can fill up the air with moisture, which will then condense into drops of water on cooler surfaces, such as mirrors and windows. Where possible, localized sources of humidity, such as clothes dryers, should be directly vented to the outdoors. To lower indoor humidity during warm, humid weather, air conditioners and/or dehumidifiers should be used. In chronically damp areas, such as basements or crawlspaces, it is often recommended that dehumidifiers be used to maintain humidity levels below 60%.
· · Temperature: Warm air holds more moisture than cold air. Condensation occurs when warm humid air comes into contact with a cold surface and the moisture condenses into water. This can often be seen on single‐pane windows, where water condenses and then runs down, causing the wood frames and sills to rot and the wall under the windows to blister. Condensation can occur on exterior walls, particularly north‐facing walls, if they are not properly insulated. Other chronically cold surfaces, such as cold water pipes, should be covered with insulation to help prevent condensation.
· · Poor Ventilation: Indoor humidity can build up if there is not enough ventilation and exchange of indoor and outdoor air. Where there is little or no air movement, such as behind dressers and cabinets, surfaces can remain cooler than surrounding areas, which can lead to increased condensation and mold growth. It is recommended that the area be ventilated and the occupants use exhaust fans (vented to the outdoors) to remove moisture from high humidity areas, particularly in bathrooms, kitchens, and laundry areas. Furniture should be moved slightly away from walls so that air can freely pass behind them. Air should be allowed to circulate between rooms and regularly ventilate to remove humid air. Fans should be used as needed.
Other things that can be done are to clean and repair gutters regularly, make sure the ground slopes down and away from the home’s foundation, and keep air conditioner drip pans and drain lines clean. In addition, in air conditioned buildings in hot and humid climates, vinyl wall coverings on the interior sides of exterior walls should not be used as these materials can trap moisture, resulting in mold growth underneath them.
In the case of floods or leaking pipes, any standing water should be promptly removed and water damaged materials should either be dried out and cleaned, or removed and replaced. Porous materials that are wet for more than 48 hours are likely to produce mold growth and should be discarded. In instances where the water damage is extensive, it is recommended that professional help, such as a commercial restoration company, be consulted.