Frequently Asked Questions

What is mold?

Mold is a type of fungus that reproduces by releasing tiny spores into the air. Those spores are everywhere — indoors and outdoors — and that's completely normal. The problem starts when spores land on a damp surface inside your home and begin to grow. In my experience, the most common triggers are slow leaks people don't know about, poor ventilation in bathrooms or crawlspaces, and water intrusion after heavy rain. Mold needs three things to grow: a food source (wood, drywall, carpet), moisture, and time. Take away the moisture and you stop the mold.

Can mold cause health problems?

Yes, though the severity varies a lot depending on the type of mold, the concentration of spores, and the individual. The most common complaints I hear from clients are persistent allergy-like symptoms — sneezing, runny nose, itchy eyes — that improve when they leave the house. People with asthma or compromised immune systems tend to be more sensitive. In some cases, certain mold species can produce mycotoxins, which are more serious. If you or your family are experiencing unexplained symptoms that seem tied to being indoors, it's worth getting the air tested. Read more about mold at https://www.epa.gov/mold **[1]: https://www.epa.gov/mold

Who can test my home or clean, fix and remediate my home for mold?

The EPA does not have a certification program for mold inspectors or mold remediations firms, nor do they keep track of such businesses. Thus finding companies that supply this service is not limited. Sometimes companies that provide radon, lead, or asbestos inspection services provide mold assessment services as another part of their business. Companies that provide water damage inspection services may help look for moisture, and some may be familiar with mold problems as well. We recommend that you ask about these potential companies' qualifications, training, and experience to vet them yourselves.

What is the difference between mold and mildew?

Mildew often used to refer to mold growth, is also a term that refers to certain kinds of mold or fungus. Molds include all species of microscopic fungi that grow in the form of multicellular filaments, called hyphae, and they can thrive on any organic matter. These surfaces can include clothing, leather, paper, and ceilings, walls, and floors of homes with moisture management problems. Mildew, on the other hand, often lives on shower walls, windowsills, and other places where moisture levels are high.

How can I tell if I have a mold problem?

The most obvious sign is visible growth — dark spots or patches on walls, ceilings, grout, or around windows. But in my experience, a lot of significant mold problems aren't visible at all. They're behind walls, under flooring, or in crawlspaces. A musty smell is often the first real clue. If your home smells musty and you can't find the source, that's usually worth investigating. Any history of water damage — a leak, flooding, condensation — is also a strong reason to have an inspection, even if you don't see anything obvious.

Why is mold growing in my home?

Almost always, the answer is moisture. Every mold problem I've investigated has a water source behind it — sometimes obvious, like a flooded basement, and sometimes subtle, like a slow pipe drip inside a wall or inadequate ventilation causing condensation. Finding and fixing that moisture source is just as important as the cleanup itself. If the water problem isn't addressed, the mold will return regardless of how thorough the remediation is.

How do molds affect people?

Molds are usually not a problem indoors unless mold spores land on a wet or damp spot and begin growing. Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. They can be immediate or delayed. Molds can also cause asthma attacks in people with asthma who are allergic to mold. Also, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people. Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold. Research on mold and health effects is ongoing. For more detailed information, consult a health professional.

What does mold smell like?

Some compounds produced by molds have strong smells and are volatile and quickly released into the air. These compounds are known as microbial volatile organic compounds (mVOCs). Because mVOCs often have strong or unpleasant odors, they can be the source of the "moldy odor" or musty smell frequently associated with mold growth. A moldy odor suggests that mold is growing in the building and should be investigated.

How do I get rid of mold?

The short answer: fix the water problem first, then address the mold. If you clean up mold without correcting the moisture source, it will come back. For small surface areas (under 10 square feet), careful cleaning with appropriate products can be sufficient. For anything larger, or for mold inside walls or HVAC systems, professional remediation is the right call. Before hiring a remediation company, I always recommend getting an independent inspection first — it gives you an unbiased scope of work to compare contractor bids against, and a standard for verifying the job was done correctly.

What are the main ways to control moisture in your home?

• Fix leaks and seepage. If water is entering the house from the outside, your options range from simple landscaping to extensive excavation and waterproofing. (The ground should slope away from the house.) Water in the basement can result from the lack of gutters or a water flow toward the house. Water leaks in pipes or around tubs and sinks can provide a place for biological pollutants to grow.

• Put a plastic cover over dirt in crawlspaces to prevent moisture from coming in from the ground. Be sure crawlspaces are well-ventilated.

• Use exhaust fans in bathrooms and kitchens to remove moisture to the outside (not into the attic). Vent your clothes dryer to the outside.

• Turn off certain appliances (such as humidifiers or kerosene heaters) if you notice moisture on windows and other surfaces.

• Use dehumidifiers and air conditioners, especially in hot, humid climates, to reduce moisture in the air, but be sure that the appliances themselves don't become sources of biological pollutants.

• Raise the temperature of cold surfaces where moisture condenses. Use insulation or storm windows. (A storm window installed on the inside works better than one installed on the outside.) Open doors between rooms (especially doors to closets which may be colder than the rooms) to increase circulation. Circulation carries heat to the cold surfaces. Increase air circulation by using fans and moving furniture from wall corners to promote air and heat circulation. Be sure that your house has a fresh air source and can expel excessive moisture from the home.

• Pay special attention to carpet on concrete floors. Carpet can absorb moisture and serve as a place for biological pollutants to grow. Use area rugs which can be taken up and washed often. In certain climates, if carpet is to be installed over a concrete floor, it may be necessary to use a vapor barrier (plastic sheeting) over the concrete and cover that with sub-flooring (insulation covered with plywood) to prevent a moisture problem.

• Moisture problems and their solutions differ from one climate to another. The Northeast is cold and wet; the Southwest is hot and dry; the South is hot and wet; and the Western Mountain states are cold and dry. All of these regions can have moisture problems. For example, evaporative coolers used in the Southwest can encourage the growth of biological pollutants. In other hot regions, the use of air conditioners which cool the air too quickly may prevent the air conditioners from running long enough to remove excess moisture from the air. The types of construction and weatherization for the different climates can lead to different problems and solutions.

Are there Federal regulations or standards regarding mold?

Standards or Threshold Limit Values (TLVs) for airborne concentrations of mold, or mold spores, have not been set. Currently, there are no EPA regulations or standards for airborne mold contaminants.

Does ultraviolet (UV) radiation from UV lamps kill mold?

If properly designed, ultraviolet germicidal irradiation (UVGI) cleaners that use ultraviolet radiation from UV lamps may destroy some molds that are growing on the moist interiors of HVAC surfaces (e.g., cooling coils, drain pans, or ductwork). But typical UVGI cleaners used in homes have limited effectiveness in killing molds. Effective destruction of some viruses and most mold and bacterial spores usually requires much higher UV exposure than is provided in a typical home unit. Furthermore, dead mold spores can still produce allergic reactions, so UVGI cleaners may not be effective in reducing allergy and asthma symptoms.

Does carpet cause indoor air quality (IAQ) problems in schools?

Carpet use in schools provides a decrease in noise, falls, and injuries. IAQ problems can be encountered with carpet and many other materials if the school has any water intrusion or moisture problem, such as a leaky roof. If carpeting remains damp, it can become a primary source for microbial growth, which frequently results in adverse health effects. Carpet and other furnishings that become water damaged should be removed and discarded or steam cleaned and thoroughly dried before reinstallation. New carpet systems (including adhesives used to adhere face fibers to backing materials, carpet cushions, and the adhesives often used to install carpets), like most new interior finishing materials, will off-gas VOCs for some time after being installed. These emissions can be significantly reduced, although not eliminated, in the first 72 hours by using proper ventilation techniques. With any floor covering system, low VOC emission products should be selected and used in school applications. Carpet also acts as a reservoir for dust, dirt, pollen, mold spores, pesticides, and other materials which may originate indoors or be brought into the indoor environment from outside. If kept very clean from the time it is installed, carpet can trap a significant amount of particles, which can be removed through regular and effective vacuuming. However, inadequate maintenance can allow large quantities of dust and debris to build up in a carpet. Some studies indicate that poorly maintained carpets can release significant quantities of particles into the air during daily activity.

Should I have the air ducts in my home cleaned?

You should consider having the air ducts in your home cleaned if: There is substantial visible mold growth inside hard surface ducts or other components of your heating and cooling system. There are several important points to understand concerning mold detection in the heating and cooling systems: • Many sections of your heating and cooling system may not be accessible for a visible inspection, so ask the service provider to show you any mold they say exists. • You should be aware that although a substance may look like mold, a positive determination of whether it is mold or not can be made only by an expert and may require laboratory analysis for final confirmation. For about 50, some microbiology laboratories can tell you whether a sample sent to them on a clear strip of sticky household tape is mold or simply a substance that resembles it. • If you have insulated air ducts and the insulation gets wet or moldy it cannot be effectively cleaned and should be removed and replaced. • If the conditions causing the mold growth in the first place are not corrected, mold growth will recur.

What about mold in large buildings?

EPA has several resources available; you can start with the Indoor Air Quality Building Evaluation and Assessment Model (I-BEAM). I-BEAM updates and expands EPA's existing Building Air Quality guidance and is designed to be comprehensive state-of-the-art guidance for managing Indoor Air Quality in commercial buildings. This guidance was designed to be used by building professionals and others interested in indoor air quality in commercial buildings. I-BEAM contains text, animation/visual, and interactive/calculation components that can be used to perform several diverse tasks.

Should I use bleach to clean up mold?

Bleach is often the first thing people reach for, but I generally don't recommend it for mold cleanup, for a few reasons. On porous surfaces like wood or drywall, bleach doesn't penetrate deeply enough to kill mold at the root — it removes the surface color but leaves the structure intact. It also produces fumes that can be harmful in enclosed spaces. If you're dealing with a small area of mold on a non-porous surface like tile, diluted bleach can work. For anything on porous materials or larger than a couple of square feet, you're better off consulting a professional.

Please note: Dead mold may still cause allergic reactions in some people, so it is not enough to kill the mold; it must also be removed.