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ArticleTechnical Article
Mold

What You Need to Know about Mold

By EPA

Categories: Remediation, Bathrooms, Kitchens, Windows, Walls & Ceilings, Health & Safety
Tagged: Air Conditioner, Asthma And Allergies, Basement, Bathroom, Dampness, Dehumidifier, EPA, Exhaust Fan, Health, Humidity, Kitchen, Moisture, Mold, Odor Control, Odors, Plumbing, Professional Cleaning Services, Relative Humidity, Safety, Ventilation, Walls

Mold itself is inescapable. It’s a fungus — a kind of plant — whose spores float in the atmosphere. In this form, it’s usually harmless. Mold only becomes a problem in the presence of moisture, particularly in places where dampness is persistent. In as little as one to two days, mold spores attach themselves to the damp surface and begin to multiply (or “grow”). Mold cannot grow without moisture. Some common examples of places where mold can persist include:

 

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  • Basements, particularly where improper outside drainage, shallow groundwater (“high water table”), plumbing leaks or persistently high humidity promote dampness and condensation.

  • In walls, where culprits such as plumbing leaks, malfunctioning rain gutters or poor exterior caulking can permanently dampen wood framing and insulation.

  • Bathrooms and kitchens, where inadequate ventilation allows moisture to build up.
Why is this important?

Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially dangerous substances called 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.

 

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. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people. Research on mold and health effects is ongoing.

What can I do about it?

It is impossible to get rid of all mold and mold spores indoors. Some mold spores will be found floating through the air and in house dust. The spores will not grow if moisture is not present. Indoor mold growth can and should be prevented or controlled by controlling moisture indoors.

 

If there is mold growth in your home, you must clean up the mold and fix the water problem. If you clean up the mold, but don't fix the water problem, then, most likely, the mold problem will come back. Following are several tips to make sure that doesn’t happen:

 

  • Fix plumbing leaks and other water problems as soon as possible. Dry all items completely.

  • Scrub mold off hard surfaces with detergent and water, and dry completely. In many instances, a portable fan will speed drying.

  • Absorbent or porous materials, such as ceiling tiles and carpet, may have to be thrown away if they become moldy. Mold can grow on or fill in the empty spaces and crevices of porous materials, so the mold may be difficult or impossible to remove completely.

  • Avoid exposing yourself or others to mold. This means wearing the proper clothes and equipment while cleaning and using effective ventilation techniques.

  • Do not paint or caulk moldy surfaces. Clean up the mold and dry the surfaces before painting. Paint applied over moldy surfaces is likely to peel.

  • If you are unsure about how to clean an item, or if the item is expensive or of sentimental value, you may wish to consult a specialist. Specialists in furniture repair, restoration, painting, art restoration and conservation, carpet and rug cleaning, water damage, and fire or water restoration are commonly listed in phone books. Be sure to ask for and check references. Look for specialists who are affiliated with professional organizations.

  • Moisture control is the key to mold control, so act quickly when water leaks or spills occur indoors. If wet or damp materials or areas are dried 24-48 hours after a leak or spill happens, in most cases mold will not grow.

  • Clean and repair roof gutters regularly.

  • Make sure the ground slopes away from the building foundation, so that water does not enter or collect around the foundation.

  • Keep air conditioning drip pans clean and drain lines unobstructed and flowing properly.

  • Keep indoor humidity low. If possible, keep indoor relative humidity below 60 percent; ideally, it should be in the 30-percent to 50-percent range. Relative humidity can be measured with a hygrometer, or humidity meter, a small, inexpensive ($10-$50) instrument available at many hardware stores.

  • If you see condensation or moisture collecting on windows, walls or pipes, dry the wet surface quickly and reduce the moisture/water source. Condensation can be a sign of high humidity.
How do I reduce humidity?
  • Vent appliances that produce moisture, such as clothes dryers, stoves and kerosene heaters to the outside where possible. Combustion appliances such as stoves and kerosene heaters produce water vapor and will increase humidity unless vented to the outside.

  • Use air conditioners and/or de-humidifiers when needed.

  • Run the bathroom fan or open the window when showering. Use exhaust fans or open windows whenever cooking, running the dishwasher or dishwashing, etc.
How do I prevent condensation?
  • Reduce humidity as outlined above.

  • Increase ventilation or air movement by opening doors and/or windows when practical. Use fans as needed.

  • Insulate cold surfaces, such as cold water pipes.

  • Increase air temperature.
Who should do the cleanup?

This depends on a number of factors. One consideration is the size of the mold problem. If the moldy area is less than about 10 square feet, in most cases, you can handle the job yourself, following the guidelines below. However:

 

  • If there has been a lot of water damage, and/or mold growth covers more than 10 square feet, consult the U.S. Environmental Protection Agency (EPA) guide, "Mold Remediation in Schools and Commercial Buildings." Although focused on schools and commercial buildings, this document is applicable to other building types.

  • If you choose to hire a contractor (or other professional service provider) to do the cleanup, make sure the contractor has experience cleaning up mold. Check references and ask the contractor to follow the recommendations in EPA's "Mold Remediation in Schools and Commercial Buildings" or the guidelines of the American Conference of Governmental Industrial Hygienists (ACGIH).

  • If you suspect that the heating / ventilation / air conditioning (HVAC) system may be contaminated with mold (it is part of an identified moisture problem, for instance, or there is mold near the intake to the system), consult EPA's guide, "Should You Have the Air Ducts in Your Home Cleaned?" before taking further action. Do not run the HVAC system if you know or suspect that it is contaminated with mold — it could spread mold throughout the building.

  • If the water and/or mold damage was caused by sewage or other contaminated water, then call in a professional who has experience cleaning and fixing buildings damaged by contaminated water.

  • If you have health concerns, consult a health professional before starting cleanup.
What to Wear When Cleaning Moldy Areas
  • Avoid breathing mold or mold spores. In order to limit your exposure to airborne mold, you may want to wear an N-95 respirator, available at many hardware stores and Internet companies for $12-$25. Some N-95 respirators resemble a paper dust mask with a nozzle on the front; others are made primarily of plastic or rubber and have removable cartridges that trap most of the mold spores from entering. In order to be effective, the respirator or mask must fit properly, so carefully follow the instructions supplied with the respirator.

  • Wear gloves. Long gloves that extend to the middle of the forearm are recommended. When working with water and a mild detergent, ordinary household rubber gloves may be used. If you are using a disinfectant, a biocide such as chlorine bleach, or a strong cleaning solution, you should select gloves made from natural rubber, neoprene, nitrile, polyurethane, or PVC. Avoid touching mold or moldy items with your bare hands.

  • Wear goggles. Goggles that do not have ventilation holes are recommended. Avoid getting mold or mold spores in your eyes.
How Do I Know When the Remediation or Cleanup is Finished?

Ultimately, this is a judgment call; there is no easy answer. In general:

 

  • You must have completely fixed the water or moisture problem before the cleanup or remediation can be considered finished.

  • You should have completed mold removal. Visible mold and moldy odors should not be present. Please note that mold may cause staining and cosmetic damage.

  • You should have revisited the site(s) shortly after cleanup and it should show no signs of water damage or mold growth.

  • People should have been able to occupy or re-occupy the area without health complaints or physical symptoms.
What You Need to Know about Mold:  Created on December 29th, 2004.  Last Modified on January 21st, 2014

 

About EPA

The mission of the Environmental Protection Agency (EPA) is to protect human health and the environment. Since 1970, the EPA has been working for a cleaner, healthier environment for the American people. At laboratories located throughout the nation, the agency works to assess environmental conditions and to identify, understand and solve current and future environmental problems.