Introduction to Molds
Basic Mold Cleanup
Ten Things You Should Know About Mold
Asthma and Mold
Health and Mold
Homes and Mold
Indoor Air Regulations and Mold
Large Buildings and Mold
Schools and Mold and Indoor Air Quality
A PDF version of these resources is available.
Molds produce tiny spores to reproduce. Mold spores waft through the indoor and outdoor air continually. When mold spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. There are molds that can grow on wood, paper, carpet, and foods. When excessive moisture or water accumulates indoors, mold growth will often occur, particularly if the moisture problem remains undiscovered or un-addressed. There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.
The key to mold control is moisture control. It is important to dry water damaged areas and items within 24-48 hours to prevent mold growth. If mold is a problem in your home, clean up the mold and get rid of the excess water or moisture. Fix leaky plumbing or other sources of water. Wash mold off hard surfaces with detergent and water, and dry completely. Absorbent materials (such as ceiling tiles & carpet) that become moldy may have to be replaced.
Molds can trigger asthma episodes in sensitive individuals with asthma. People with asthma should avoid contact with or exposure to molds.
Mold growth may be a problem after flooding. EPA's Fact Sheet: Flood Cleanup: Avoiding Indoor Air Quality Problems - discusses steps to take when cleaning and repairing a home after flooding. Excess moisture in the home is cause for concern about indoor air quality primarily because it provides breeding conditions for microorganisms. This fact sheet provides tips to avoid creating indoor air quality problems during cleanup. U.S. EPA, EPA Document Number 402-F-93-005, August 1993.
Federal Emergency Management Agency (FEMA): (800) 480-2520; www.fema.gov mitigation website: www.fema.gov/mit publications on floods, flood proofing, etc.
University of Minnesota, Department of Environmental Health & Safety - www.dehs.umn.edu/iaq/flood.html. "Managing Water Infiltration Into Buildings." A Systematized Approach for Remediating Water Problems in Buildings due to Floods, Roof Leaks, Potable Water Leaks, Sewage Backup, Steam Leaks and Groundwater Infiltration. Questions and comments may be directed to: Neil Carlson, M.S., CIH, Department of Environmental Health & Safety, University of Minnesota, or Arif Quraishi, M.E., Vice President, Special Projects, Indoor Environments Division, Institute for Environmental Assessment, Inc.
Molds can trigger asthma episodes in sensitive individuals with asthma (See Asthma Section above); molds can also trigger allergies in sensitive individuals.
EPA's publication, Indoor Air Pollution: An Introduction for Health Professionals, assists health professionals (especially the primary care physician) in diagnosis of patient symptoms that could be related to an indoor air pollution problem. It addresses the health problems that may be caused by contaminants encountered daily in the home and office. Organized according to pollutant or pollutant groups such as environmental tobacco smoke, VOCs, biological pollutants, and sick building syndrome, this booklet lists key signs and symptoms from exposure to these pollutants, provides a diagnostic checklist and quick reference summary, and includes suggestions for remedial action. Also includes references for information contained in each section. This booklet was developed by the American Lung Association, the American Medical Association, the U.S. Consumer Product Safety Commission, and the EPA. EPA Document Reference Number 402-R-94-007, 1994.
Allergic Reactions - excerpted from Indoor Air Pollution: An Introduction for Health Professionals section on: Animal Dander, Molds, Dust Mites, Other Biologicals.
"A major concern associated with exposure to biological pollutants is allergic reactions, which range from rhinitis, nasal congestion, conjunctival inflammation, and urticaria to asthma. Notable triggers for these diseases are allergens derived from house dust mites; other arthropods, including cockroaches; pets (cats, dogs, birds, rodents); molds; and protein-containing furnishings, including feathers, kapok, etc. In occupational settings, more unusual allergens (e.g., bacterial enzymes, algae) have caused asthma epidemics. Probably most proteins of non-human origin can cause asthma in a subset of any appropriately exposed population."
Consult the Centers for Disease Control (CDC) website
- CDC's National Center for Environmental Health (NCEH) has a toll-free telephone number for information and FAXs, including a list of publications: NCEH Health Line 1-888-232-6789.
- CDC's "Molds in the Environment" Factsheet
Stachybotrys or Stachybotrys atra (chartarum) and health effects
- CDC's "Questions and Answers on Stachybotrys chartarum and other molds"
The EPA publication, "A Brief Guide to Mold, Moisture, and Your Home", is available here in HTML and PDF formats. This Guide provides information and guidance for homeowners and renters on how to clean up residential mold problems and how to prevent mold growth. A printed version will be available soon.
Biological Pollutants in Your Home - This document explains indoor biological pollution, health effects of biological pollutants, and how to control their growth and buildup. One third to one half of all structures have damp conditions that may encourage development of pollutants such as molds and bacteria, which can cause allergic reactions -- including asthma -- and spread infectious diseases. Describes corrective measures for achieving moisture control and cleanliness. This brochure was prepared by the American Lung Association and the U.S. Consumer Product Safety Commission. EPA Document Reference Number 402-F-90-102, January 1990.
Moisture control is the key to mold control, the Moisture Control Section from Biological Pollutants in Your Home follows:
Water in your home can come from many sources. Water can enter your home by leaking or by seeping through basement floors. Showers or even cooking can add moisture to the air in your home. The amount of moisture that the air in your home can hold depends on the temperature of the air. As the temperature goes down, the air is able to hold less moisture. This is why, in cold weather, moisture condenses on cold surfaces (for example, drops of water form on the inside of a window). This moisture can encourage biological pollutants to grow.
There are many ways to control moisture in your home:
Should You Have the Air Ducts in Your Home Cleaned? - excerpt on duct cleaning and mold follows, please review the entire document for additional information on duct cleaning and mold.
You should consider having the air ducts in your home cleaned if:
There is substantial visible mold growth inside hard surface (e.g., sheet metal) ducts or on other components of your heating and cooling system. There are several important points to understand concerning mold detection in heating and cooling systems:
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.
EPA has a number of resources available, you can start with "Building Air Quality: A Guide for Building Owners and Facility Managers" and the "Building Air Quality Action Plan"
How to Identify the Cause of a Mold and Mildew Problem.
Mold and mildew are commonly found on the exterior wall surfaces of corner rooms in heating climate locations. An exposed corner room is likely to be significantly colder than adjoining rooms, so that it has a higher relative humidity (RH) than other rooms at the same water vapor pressure. If mold and mildew growth are found in a corner room, then relative humidity next to the room surfaces is above 70%. However, is the RH above 70% at the surfaces because the room is too cold or because there is too much moisture present (high water vapor pressure)?
The amount of moisture in the room can be estimated by measuring both temperature and RH at the same location and at the same time. Suppose there are two cases. In the first case, assume that the RH is 30% and the temperature is 70oF in the middle of the room. The low RH at that temperature indicates that the water vapor pressure (or absolute humidity) is low. The high surface RH is probably due to room surfaces that are "too cold." Temperature is the dominating factor, and control strategies should involve increasing the temperature at cold room surfaces.
In the second case, assume that the RH is 50% and the temperature is 70oF in the middle of the room. The higher RH at that temperature indicates that the water vapor pressure is high and there is a relatively large amount of moisture in the air. The high surface RH is probably due to air that is "too moist." Humidity is the dominating factor, and control strategies should involve decreasing the moisture content of the indoor air.
The Agency's premier resource on this issue is the Indoor Air Quality Tools for Schools kit. Our schools-related resources on the web start at: epa.gov/iaq/schools.
The asthma companion piece for the IAQ Tools for Schools kit, titled Managing Asthma in the School Environment (epa.gov/iaq/schools/asthma) has been recently published. This publication has a section entitled Clean Up Mold and Moisture Control at: epa.gov/iaq/schools/asthma/eat-cumcm.htm
Moisture problems in school buildings can be caused by a variety of conditions, including roof and plumbing leaks, condensation, and excess humidity. Some moisture problems in schools have been linked to changes in building construction practices during the past twenty to thirty years. These changes have resulted in more tightly sealed buildings that may not allow moisture to escape easily. Moisture problems in schools are also associated with delayed maintenance or insufficient maintenance, due to budget and other constraints. Temporary structures in schools, such as trailers and portable classrooms, have frequently been associated with moisture and mold problems.
Suggestions for Reducing Mold Growth in Schools
Reduce Indoor Humidity:
- Vent showers and other moisture-generating sources to the outside.
- Control humidity levels and dampness by using air conditioners and de-humidifiers.
- Provide adequate ventilation to maintain indoor humidity levels between 30-60%.
- Use exhaust fans whenever cooking, dishwashing, and cleaning in food service areas.
Inspect the building for signs of mold, moisture, leaks, or spills:
- Check for moldy odors.
- Look for water stains or discoloration on the ceiling, walls, floors, and window sills.
- Look around and under sinks for standing water, water stains, or mold.
- Inspect bathrooms for standing water, water stains, or mold.
- Do not let water stand in air conditioning or refrigerator drip pans.
Respond promptly when you see signs of moisture and/or mold, or when leaks or spills occur:
- Clean and dry any damp or wet building materials and furnishings within 24-48 hours of occurrence to prevent mold growth.
- Fix the source of the water problem or leak to prevent mold growth.
- Clean mold off hard surfaces with water and detergent, and dry completely.
- Absorbent materials such as ceiling tiles, that are moldy, may need to be replaced.
- Check the mechanical room and roof for unsanitary conditions, leaks, or spills.
Prevent moisture condensation:
- Reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls, roof, or floors) by adding insulation.
Floor and carpet cleaning:
- Remove spots and stains immediately, using the flooring manufacturer’s recommended techniques.
- Use care to prevent excess moisture or cleaning residue accumulation and ensure that cleaned areas are dried quickly.
- In areas where there is a perpetual moisture problem, do not install carpeting (i.e., by drinking fountains, by classroom sinks, or on concrete floors with leaks or frequent condensation).
EPA's Antimicrobial Information Hotline
(703) 308-0127/(703) 308-6467
The Antimicrobials Information Hotline provides direct answers to questions concerning current antimicrobial issues. Please call during normal business hours (Monday - Friday 9 a.m. to 5 p.m.) or leave a message after hours. The information provided can cover issues relevant to any or all antimicrobial pesticides including health & safety issues, registration and re-registration issues, as well as information on pesticide laws, rules, and regulations relating to antimicrobials.