Mold, Mildew and Fungi

Josh Feinmann, Clean Air Advice
June 2006

What are Molds?

Molds are organisms that play a natural role in the environment by breaking down and digesting organic material. Mold can be found indoors or outdoors and is often referred to as fungi or mildew. Regardless of how they are known; all mold, fungi and mildew are classified as part of the Fungi Kingdom.

Molds reproduce by emitting microscopic spores. These spores are small enough that they can easily remain suspended in air and travel great distances. Mold spores can be found everywhere both indoors and outdoors. It is impossible to completely eliminate mold spores from indoor environments, however these spores will not grow unless moisture is present. Poor indoor air quality due to mold spores will fluctuate from season to season, day to day, and hour to hour based on the concentration of suspended mold spores.

Unless mold spores land in wet or damp areas indoors, they rarely cause problems. However, as molds begin to grow they digest whatever they are growing on. If left unchecked, this mold growth can damage buildings by rotting wood, damaging drywall and causing structural damage. There are even potential human health effects associated with the poor indoor air quality commonly found in the presence of mold growth.

Where and Why Does Mold Grow?

In order for mold to grow indoors it needs only two things, moisture and food. Moisture is the most important factor for growth, controlling moisture in your home helps to limit mold growth. Not a lot of water is needed for mold to thrive; a little condensation can be more than enough. Common places for mold to grow include bathroom tile and grout, basement walls, areas around windows and sinks. Common sources for water and condensation include plumbing fixtures, humidification systems, sprinkler systems, roof leaks, and high levels of humidity or cold spots.

Moisture problems are often not easy to see. There are many common locations of hidden moisture, often resulting in hidden mold growth. Some of these possible locations are inside walls where pipes and wires are run; condensate drain pans in air handling units; porous liners inside duct work; roofing material above ceiling tiles; back sides of drywall, paneling and wallpaper; as well as the underside of carpet.

Mold is not picky about what food or nutrient source it uses to grow. Mold can grow on practically any organic material. Coincidentally, most buildings contain an abundance of organic material such as paper, cloth, wood, plant material, and soil. Temperature is usually not an issue pertaining to mold growth. Certain types of molds grow well in warm areas while others grow well in cold ones, such as bread stored in a refrigerator. Multiple types or varieties of mold can often be found growing in the same location. Conditions such as light, moisture levels and temperature will slightly favor one species of mold over another, however mold can grow in just about any area.

Health Effects Due to Inhaling Mold or Mold Spores

Inhaling mold commonly found indoors can lead to health problems in some people. Molds produce allergens, irritants and in some cases toxic substances known as mycotoxins. In sensitive individuals, simply touching or inhaling mold or mold spores can cause allergic reactions. Mold can cause health effects such as allergic reactions whether it is dead or alive.

Allergic reactions to mold are very common and their effects can be either immediate or delayed. Individuals can become sensitive to mold after as little as one exposure. Repeated exposure can potentially increase sensitivity. Allergic responses due to poor indoor air quality from mold include headache, sneezing, runny nose, red eyes and skin rash. Mold exposure can also induce asthma attacks in those with asthma. Even those not allergic to mold are not completely immune. Mold can irritate the eyes, skin, nose, throat and lungs even in non-allergic individuals.

Other health effects associated with mold exposure can be more severe although more rare. Breathing in mold can cause hypersensitivity pneumonitis, an uncommon disease resembling bacterial pneumonia; chronic sinusitis; and opportunistic infections in those with weakened immune systems.

Black mold and toxic mold are common buzzwords used to describe types of mold and their effects. Toxic mold is a term used to refer to types of mold that produce mycotoxins while black mold usually refers to a specific type of mold, Stachybotrys chartarum. Toxic mold or toxigenic fungi are molds that produce potentially toxic byproducts called mycotoxins. These types of molds are very commonly found in moisture-damaged buildings. However they can occur in any environment in which mold will grow. You cannot tell whether mold is producing mycotoxins just by looking at it. Exposure to mycotoxins occurs though inhalation, ingestion and skin contact. Certain mycotoxins are known to cause health effects in people while little is known about the effects of many other types. Complaints of symptoms associated with "toxic mold" and "black mold" due to exposure to mycotoxins include depression, headaches, fatigue, muscle and joint pain, nausea, respiratory disorders, chills, fever, sensitized skin, nosebleeds, and central and peripheral nervous system effects.

Detection

Certain compounds produced by molds have strong smells and are quickly released into the air. These compounds are known as microbial volatile organic compounds (mVOCs). These compounds have a very strong unpleasant odor and are commonly the source of the moldy smell associated with mold growth. A moldy odor suggests that mold is growing in the building. However, some molds do not give off strong odors and must be found through visual inspection. Check areas commonly associated with mold growth as well as any areas that possibly have moisture problems. Smell and sight are the most common techniques used for mold detection making it fairly easy to determine if you have a problem. In certain situations it may be appropriate to pay a contractor to conduct mold testing in your home. However, be aware that mold testing can be expensive and require specialized equipment not available to the general public.

Removal

The way in which mold is removed depends on the size of the problem. In general if the moldy area is less than about 10 square feet (3 ft by 3 ft) the job can be handled yourself. However, if there is a lot of water damage or mold covers more than 10 square feet, you may want to contact a licensed contractor to do the clean up. A contractor will be able to conduct clean up and removal of the mold with out causing further contamination to the rest of your home.

If the area is small the mold can be killed using a simple biocide such as chlorine bleach. The use of such biocides is not recommended as a routine clean up and should always be used in a well-ventilated area. Never mix chlorine bleach with other cleaning solutions or products containing ammonia because toxic fumes could be produced. Also, it is not enough just to kill the mold. Dead mold is allergenic and can cause allergic reactions and various other health effects. To remove the problem, the mold must be removed after it is killed.

Prevention

The most important method for preventing mold growth is controlling the moisture in your home. Special attention should be given to hidden areas that could be wet. Areas behind walls, crawl spaces and attics are often over looked and not carefully dried when wet. Any wet area should be completely dried within 48 hours to prevent mold growth.

Routine maintenance is another important preventative technique. Furnace humidifiers should be cleaned regularly to prevent mold growth. Ducts where humidifiers are located should be checked to ensure there is no water leakage. Any stand-alone humidifiers should be cleaned very frequently paying special attention that the filters to prevent the spread of mold spores. Any carpet around humidifiers should be closely watched for wetness. The relative indoor humidity should be kept below 60%. Anything above 60% is likely to cause condensation, leading to mold growth.

HVAC systems should be routinely checked. Contamination in an HVAC system can spread mold throughout the building. Drain or condensate pans should be checked regularly to ensure that they are clean and draining properly. If the pans become contaminated with mold it may allow moisture and mold to enter the HVAC system and contaminate the ventilation ducts.

Bathroom and toilet areas should be closely monitored for water leaks. Signs of water damage include rippling wallpaper, cracked drywall tape and peeling paint. These are common signs of a water leak followed by a hidden mold problem. Any water leak must be cleaned up, fixed at the source, and thoroughly dried within 48 hours to prevent mold growth.

The most important preventative measure is to control moisture. Moisture control can prevent or at least greatly limit mold growth, in turn protecting your home's indoor air quality and your health.

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• Fungus and Mold may cause Chronic Sinusitis
• Do You Have a Mold Problem?
• What Are You Breathing?
• 12 Steps to Improve Indoor Air Quality