What is mold?
Molds are microscopic fungi that thrive on moist or damp areas to grow. This includes fungi such as mushrooms and yeasts. When present in clothing, it is often times referred to as mildew. They are part of the natural environment: spoiled food contains molds, decaying leaves rot because of them and wet fabrics left in a damp place develop musty odors due to the presence of these fungi.
They are useful to people in many ways. For instance, the penicillin drug is derived from a specific mold type. Various types of mold are used to produce various chesses, alcohols, and chemicals used in different industries. However, extensive mold growth, especially inside a building, can be harmful to people.
Household molds can damage furniture and clothing. It is important to recognize the presence of molds at home early on to avoid developing allergic reactions to these microscopic fungi.
What does mold look like?
Mold can look white, gray, black, brown, yellow or greenish. Mold colonies may appear cottony, velvety, granular, leathery and glassy.
What causes mold to develop?
Mold needs these conditions before it can begin to grow inside a building:
• Mold spores
• A food source (e.g. wood, drywall, cotton)
• Darkness (mold can’t grow under ultraviolet light)
• Warmth (mold can’t grow in freezing temperatures)
• Moisture (e.g. water leaks, humidity, condensation)
Accordingly, moisture is really the key cause of mold growth since the other conditions on the list are always going to be present in homes.
How do I know if I have mold?
There are three basic indications that you may have a mold problem:
1) A musty, earthy or mildewy odor. You may notice the odor in a specific area of the property. Sometimes mold lives behind walls, behind wallpaper or underneath carpeting so you may not immediately associate the smell with mold.
2) The appearance of mold: Some mold growth is visually obvious and easy to distinguish. However, sometimes mold may just look like discoloration on the wall or you might notice some water marks indicative of moisture behind the walls. If either of these scenarios are the case, mold may be the culprit.
3) Health symptoms: If you feel listless, congested and experience watering of the eyes while in your home or business, these can all be signs of presence of mold. It is not uncommon for a person who lives in a that has mold to feel better while our of the home and suddenly feel ill the minute they step through their front door.
How does mold get into a building?
Molds are decomposers of organic material such as wood, plants and animals. Mold and mold spores are found in high concentrations wherever there is dead matter such as a pile of leaves, manure or compost.
Outdoor mold spores commonly can enter a building through the air or by becoming attached to people, animals, or other materials that are moved into a building. Mold spores are very small and cannot be seen with the naked eye. A spore is a mold colony’s “seed” and is released natural into the environment to colonize. Spores are resilient and are built to with stand extreme environments so the spread of colonization reaches a larger area. Once the mold spores settle on to a viable substrate they will grow into a mold colony. A visible mold colony can house millions of spores. An area the size of a postage stamp can contain up to 65,000,000 (65 million) spores. This is more than enough to potentially spread across the interior of a property and cause mold growth where conditions are ideal.
How can I prevent mold from growing?
Mold Prevention Tips from the Centers for Disease Control and Prevention:
• Keep the humidity level in your home between 40% and 60%. Use an air conditioner or a dehumidifier during humid months and in damp spaces, like basements.
• Be sure your home has enough ventilation. Use exhaust fans which vent outside your home for kitchens and bathrooms. Make sure your clothes dryer vents outside your home.
• Fix any leaks in your home’s roof, walls, or plumbing so mold does not have moisture to grow.
• Clean up and dry out your home thoroughly and quickly (within 24 – 48 hours) after flooding.
• Add mold inhibitors to paints before painting.
• Clean bathrooms with mold-killing products.
• Remove or replace carpets and upholstery that have been soaked and cannot be dried promptly. Consider alternatives to carpet in rooms or areas such as bathrooms or basements that may have a lot of moisture.
Are there harmful and non-harmful molds?
There are only a few molds that can cause infection in healthy humans. Some molds cause infections only in people with compromised immune systems. The biggest health problem from exposure to mold is allergy and asthma in susceptible people. There are more than 100,000 types of mold. Good information has been developed for only a small number of these molds – at least in terms of their effects on human health. Most people tolerate exposure to moderate levels of many different molds without any apparent adverse health effects.
Some molds produce powerful chemicals called “mycotoxins” that can produce illness in animals and people. Scientific knowledge about the health effects of these toxins on humans is quite limited.
Does mold affect everyone the same way?
In fact only about 20% percent of the human population is naturally sensitive to mold. However, the rest of the population can also develop sensitivity if exposed to high concentrations of mold for a long time.
Some individuals have a genetic makeup that puts them at risk for developing allergies to mold. People who have an allergy to mold, especially if they also have asthma, can become ill from exposure to a small amount of mold. Individuals also seem to be quite different in their response to exposure to the toxic chemicals that some molds release. These differences between individuals contribute to the difficult question of determining safe exposure limits for mold
How much exposure is harmful?
No one knows the answer to this question for several reasons. Individuals are very different with respect to the amount of mold exposure they can tolerate. Children under the age of one year may be more susceptible to the effects of some molds than older individuals. Measuring or estimating “exposure” levels is very difficult. “Exposure” means the amount of mold (microscopic spores and mold fragments) that gets into a person usually by breathing, but also by eating or absorption through the skin. For example, a building may have a lot of mold in the walls but very little of that mold is getting into the air stream. In that case the people working or living in that building would have little mold exposure.
What symptoms do molds commonly cause?
Mold can cause illness in several ways:
• Irritation: Exposure to mold can irritate the eyes, nose and upper breathing passages. Symptoms of irritation include burning eyes, nasal congestion, coughing and post nasal drip.
• Allergy: Many people become allergic to mold and develop hay fever or asthma symptoms such as itchy, watery eyes, nasal congestion, sneezing, chest tightness, cough and wheezing.
• Toxins: Some molds create chemicals, called toxins that can cause illness. While much remains unknown about mold toxins, it appears that some molds produce toxins that can have effects on the skin, the respiratory system, the immune system and the nervous system.
• Infection: Some molds can also cause infection, such as chronic sinus infections. Other types of mold induced infections are much less common and occur mainly among people with weakened immune systems. Examples of individuals with weakened immune systems include those with HIV infection, those receiving chemotherapy and the elderly. Children and pregnant women may also be at increased risk.
Can mold exposure cause brain damage or death?
Although some “experts” claim that individuals have brain damage or have died because of exposure to mold and especially mold toxins, there is no good science at this time to support these claims. Consequently it is prudent to minimize one’s exposure to really moldy environments. By “really moldy” we mean where there are large visible areas of mold (more than a few square feet) or the building has a “musty” odor because of hidden mold growth. There are many epidemiological studies showing that people who live in houses with dampness have many more health problems, especially respiratory, than do people who live in dry houses. This association does not “prove” that it is the mold that is responsible for the increase in illness. However, it does support the assertion that it is not wise to live in damp, moldy buildings.
What is Stachybotrys chartarum or “Black Mold”?
Stachybotrys chartarum is a greenish-black mold, often referred to as “Black Mold;” however, there are many other types of mold that can be greenish-black in color. Given the right conditions, some strains of Stachybotrys chartarum, as well as certain other types of mold, can produce toxic substances called mycotoxins. These types of molds are sometimes called “Toxic Mold.” All molds should be treated the same with regard to potential health risks and removal. No matter what type of mold is present, or whether or not it can produce mycotoxins, it should be removed promptly, with the appropriate precautions taken to limit exposure.
Does tighter building construction promote mold development?
Tighter building construction does not by itself promote mold growth, but tight construction combined with some poor choices in design, building materials or operations can increase the probability of mold growth. What do we mean? The tighter the building construction the less air exchange there is between the inside air and the outside air. Whatever gets into the inside air stays there longer than it would in a house with loose construction. Moisture that gets into the air from activities such as cooking, bathing and even breathing will remain in a tight house longer than it would in a loose house. That’s why exhaust fans should be installed in bathrooms and kitchens and vented to the outside. Clothes dryers should also be vented to the outside.
Tight construction permits control of the air exchange between the inside and the outside and can prevent the deposition of moisture in walls and roofs. Controlling moisture, including indoor relative humidity is the key to preventing mold growth. Tight building construction when combined with source control of moisture (exhaust fans) and controlled ventilation (intentional introduction of outside air) reduces the probability of mold growth in a building. Controlled ventilation can be provided by a duct that brings outside air to the return side of the air handler of a forced air system. A timing device or fan cycler can be programmed to have the air handler turn on for a specified number of minutes each hour even when there is no call for heating or cooling. In cold climates controlled ventilation is frequently provided by a heat recovery ventilator (HRV).
Do new building materials (e.g. drywall, paper faced gypsum board) promote mold growth?
Mold needs water, a nutrient source, oxygen and favorable temperature to grow. Many species of mold love paper faced gypsum board. Why? Making paper involves the mechanical and chemical processing of wood. Paper is largely pre-digested so it is easy for mold to get nutrients from the paper. But unless there is enough moisture present mold can’t grow on the paper. If paper faced gypsum board is kept dry, it can be used and still not have mold. This material is kept dry by controlling the interior relative humidity, keeping rain from entering roofs and walls, and NOT using paper faced gypsum in areas that are likely to get wet. This means no paper faced gypsum board in shower and tub areas. Cement board, mortar or non-paper faced gypsum can safely be used in these damp areas because these products do not contain nutrients to support mold growth.
Should I use bleach to get rid of mold?
No. Although bleach will kill and decolorize mold, it does not remove mold. Dead mold can still cause allergic reactions. It is not necessary to kill mold to remove mold. Soap and water and scrubbing can remove mold from hard surfaces. The Environmental Protection Agency (EPA), the Center for Disease Control (CDC) and the New York City Health Department agree that bleach or other biocides should not routinely be used to clean up mold.
Is it possible to completely eliminate mold from the inside of a home or office building?
The answer depends upon what is meant by “completely eliminate mold.” To keep a building completely free of mold spores requires very efficient air filtration and is only accomplished in special situations such as hospital operating rooms and manufacturing “clean rooms.” Remember, mold spores are in the outside air virtually all the time and some of them will get inside buildings.
However, it is possible to keep mold from growing inside a building. Moisture control is the key to controlling mold in interior spaces. Air filtration can contribute to lowering mold spores in the air but is secondary to moisture control.
What can I save and what should I toss?
In general, porous substances that are growing mold, such as paper, rags, wallboard, and rotten wood, should be bagged and thrown out. Harder materials such as glass, plastic, or metal can be kept after they are cleaned and disinfected
I have mold in my basement but no one ever goes down there. Can this be a problem?
Yes, it is possible that contaminants can enter small openings in the ventilation system and be distributed to other parts of the home.
Can air duct systems become contaminated with mold?
Yes, air duct systems can become contaminated with mold, either by supporting mold growth inside (e.g., from a dirty or clogged air conditioning pan, due to over-humidification of system, etc.) or by being a means of circulating and distributing spores from one location to other parts of the home.