Mold in the Home & Schools

• Too much mold in homes and schools is common. Mold grows in moist, dark, humid areas that may have water coming in from leaking roofs, pipes, etc.
• Mold exposure is associated with health problems, such as allergic symptoms.
• Testing for mold in a home or school is usually not necessary.
• Large amounts of mold damage should be cleaned and repaired by professionals wearing appropriate personal safety gear and sealing the area.

Molds are fungi, such as mildew, yeasts, and mushrooms, that are present everywhere, both indoors and outdoors. No one knows for sure how many species of fungi exist, but they are in the thousands. Molds commonly found in homes include Penicillium, Cladosporium, Aspergillus, Alternaria, Stachybotrys, and many others. Homes built close to bodies of water like ponds, lakes, or rivers, and homes built in wooded areas are likely to have a large variety of molds growing outdoors. Outdoor molds are carried indoors by wind, the fur of pets, or clothing.

Mold can grow almost anywhere there is water, high humidity, or damp conditions. Molds are often found in homes and schools that have been flooded or have had water leaks (such as from roofs, windows, or pipes. Mold grows faster in dark spaces with warm temperatures, high humidity, and poor airflow.¹ Mold can “feed’ on paper, fabric, cellulose, wallpaper glue, sheetrock, wood, soap scum, leather, upholstery, and many other surfaces. Molds reproduce by making small spores that can enter the air, settle on wet surfaces, and grow to the visible forms of mold commonly seen in homes and schools. As fungi grow, they can produce chemicals called “volatile organic compounds” that cause the musty, sour, moldy smell.¹ Under some circumstances, some fungi can produce chemicals (termed mycotoxins). As climate change leads to higher temperatures, increased sea levels, and increases in severe storms and flooding, there can be more instances of unwanted water leaking into homes. This creates opportunities for mold growth.

Damp indoor spaces alone may produce air contaminants and odors which may cause irritation of the eyes, nose, throat and skin, asthma or asthma-like symptoms.¹³ Some people may experience general discomfort such as headaches, fatigue, and problems concentrating.^5,11 There is increasing evidence to suggest that indoor dampness is associated with people developing asthma and causing symptoms in those who have asthma.¹⁵ Chemicals (such as those released) from deteriorating building materials), dust mites and pests growing in a wet and warm environment, may also play a role in worsening asthma and allergies.^11,12

Children can be exposed to molds in the home and at school or preschool. At home, mold exposure is commonly found in bathrooms, but may be in the living area, meal areas, or basement. In schools, bathrooms, shower rooms, gyms, and science labs are environments suitable for mold growth. Mold exposure can also occur in any area where water from a leak comes in contact with paper, fabric, rugs, wallpaper glue, sheetrock, wood, and other surfaces. If disturbed, mold can release spores (usually not visible) that get inhaled. You can get mold on your skin or swallow mold if you eat spoiled food like moldy bread or sauces. Most people do not develop symptoms from such exposures. Those whose immune systems are already severely weakened may experience health problems

• Allergy (Sensitization): Some people are allergic to molds and may have a stuffy or runny nose, throat dryness, wheezing, difficulty breathing, or dry cough.¹ This means someone has a special sensitization and may have developed antibodies to mold. Parents with allergies, skin rashes (eczema), or asthma are more likely to have children who develop these allergies.^1,2,3,7,12 There have been some reported associations between prenatal mold exposure and an increased risk of eczema in children.⁸ For those with such conditions, symptoms may worsen with exposure to mold and usually decrease after the mold is
• Irritant Symptoms: Some people may experience general irritant symptoms like itchy or teary eyes, headaches, nasal congestion fatigue, or generalized weakness, when exposed to mold or damp spaces, even if they do not have a mold allergy.¹⁴
• Pneumonia: Rarely, some people may develop a reaction in the lungs (hypersensitivity pneumonitis), due to other types of antibodies to mold.^1,10
• Local or Systemic Infections: Sometimes people get minor skin infections from fungi, such as athlete’s foot, which is more related to chronically moist areas in the skin crevices, and not related to water intrusion and mold in a building. A mold infection in the lungs is a very rare reaction that can occur in some people who have weakened immune systems and are more likely to experience infections.

If you think that your children have symptoms related to mold exposure in your home or school, they should see a doctor. If you suspect the exposure is from school, you should also notify the school nurse or administrators. Current evidence indicates that allergies are most often associated with molds, but could also be related to other exposures, such as cockroaches, dust, or other agents in the indoor environment.  Many symptoms associated with mold exposure are also caused by other illnesses. The amount of mold exposure (small spot in bathtub versus large area of extensive mold growth due to flooding) is also a factor in seeking medical attention. We do not endorse or recommend testing of the blood or urine for mycotoxins.

The best way to reduce mold exposure in your home is to remove water and moisture sources. Fix leaks, dry damp areas, and lower indoor air humidity (e.g., use a dehumidifier in basements; open a window while taking a shower in bathrooms with no exhaust fan or vent). The best way to clean mold from small area surfaces (less than 3 ft by 3 ft) such as shower walls is to use detergent and water. Additional information about mold and mold removal can be found at the EPA Guide to Mold and The EPA web site Mold Cleanup in Your Home. For larger areas, it is best to contact a professional mold remediation.

These steps will limit mold growth:

• In schools, personnel must correct leaks and other sources of moisture, and safely remove damp, water-stained, moldy ceiling tiles, and other moldy materials.
• Fix leaky plumbing and leaks in the building envelope as soon as possible.
• Watch for condensation/wet spots. Fix source(s) of moisture as soon as possible.
• Prevent moisture due to condensation by increasing the temperature or reducing humidity.
• To increase surface temperature, insulate or increase air flow.
• To reduce the moisture level in air, repair leaks, increase air flow (if outside air is cold and dry), or dehumidify (if outdoor air is warm and humid).
• Keep heating, ventilation, and air conditioning drip pans clean, flowing, and unblocked.
• Vent moisture-generating appliances, such as dryers, to the outside.
• Maintain low indoor humidity, below 65% relative humidity (RH)1, ideally 30-50%.
• Allow good air circulation between furniture and surfaces like floor, ceiling, and wall
• Perform regular building/HVAC inspections and maintenance as scheduled.
• Clean and dry wet or damp spots within 48 hours. 
• Don’t let foundations stay wet. Provide proper drainage. Slope ground away from the foundation.
• In schools, maintenance personnel may be able to clean up small areas of mold. Masks, gloves, and other personal protective equipment should be worn. The best way to eliminate mold is to make sure that the source of leaking water is stopped.
• Mold spores are difficult to kill and some will remain in a home or school even after a cleanup. It is very important to reduce or eliminate moisture in areas prone to mold growth. This can be done by use of exhaust fans in bathrooms and increased ventilation in school rooms. If moisture remains, mold will grow again.

If you find areas that are damp, or smell musty, you do not have to do mold testing. Simply identify and correct sources of unwanted water leaks and clean up the moldy areas. Mold testing is expensive, time-consuming, and the results are not always related to health risk. The Centers for Disease Control and Prevention does not recommend routine sampling for molds. If air sampling for molds has already occurred, you can interpret the results.  It is common to find mold spores indoors since most come in from the outside. Usually, indoor measurements are compared to outside.  If the molds measured inside are much higher than those outside, it suggests that there is a location for mold growth inside, usually indicating that there is an area of water leakage that needs fixing. No relationship exists between the level of mold spores and specific health problems.

• CDC: Mold
• EPA: “A Brief Guide to Mold, Moisture, and Your Home”
• EPA Fact Sheet: Mold in Schools
• EPA: Interactive Mold House Tour
• Western States PEHSU: Green Cleaning, Sanitizing and Disinfecting: A Toolkit for Early Care and Education
• gov: Mold, Moisture, and Mildew
• gov: Remediation and Prevention of Mold Growth and Water Damage in Public Schools and Buildings to Maintain Air Quality
• Massachusetts Department of Public Health: Asthma and Your Environment