The most effective method for mold testing involves taking an indoor air sample, and an outdoor air sample for comparison. Also, a physical scraping can be placed on a microscope slide and sent to the lab for evaluation. The combination of air and physical sampling provides a complete list of every type of mold spore that is present.

What is Mold?
Molds are fungi. Molds grow throughout the natural and built environment. Tiny particles of mold are present in indoor and outdoor air. In nature, molds help break down dead materials and can be found growing on soil, foods, plant matter, and other items. Molds produce microscopic cells called “spores” which are very tiny and spread easily through the air. Live spores act like seeds, forming new mold growths (colonies) when they find the right conditions.

What does mold need to grow?
Mold only needs a few simple things to grow and multiply:

  • Moisture
  • Nutrients, such as wood, drywall, carpet, paper products
  • Suitable conditions, such as temperature range

Homes contain the nutrients and suitable conditions but controlling excess moisture is the key to preventing and stopping indoor mold growth.

Should I be concerned about mold in my home?
Mold should not be permitted to grow and multiply indoors. When this happens, health problems can occur and building materials, goods and furnishings may be damaged.

Can mold make me and my family sick?
Mold can affect the health of people who are exposed to it. People are mainly exposed to mold by breathing spores or other tiny fragments. People can also be exposed through skin contact with mold contaminants (for example, by touching moldy surfaces) and by swallowing it.

The type and severity of health effects that mold may produce are usually difficult to predict. The risks can vary greatly from one location to another, over time, and from person to person.

What symptoms might I see?
The most common health problems caused by indoor mold are allergy symptoms. Although other and more serious problems can occur, people exposed to mold commonly report problems such as:

  • Nasal and sinus congestion
  • Cough
  • Wheezing/breathing difficulties
  • Sore throat
  • Skin and eye irritation
  • Upper respiratory infections (including sinus)

Are the risks greater for some people?
There is wide variability in how different people are affected by indoor mold. However, the long term presence of indoor mold growth may eventually become unhealthy for anyone. The following types of people may be affected more severely and sooner than others:

  • Infants and children
  • Elderly people
  • Individuals with respiratory conditions or sensitivities such as allergies and asthma
  • Persons having weakened immune systems (for example, people with HIV infection, chemotherapy patients, organ transplant recipients)

Those with special health concerns should consult a medical professional if they feel their health is affected by indoor mold.

Are some molds more hazardous than others?

Some types of mold can produce chemical compounds (called mycotoxins) although they do not always do so. Molds that are able to produce toxins are common. In some circumstances, the toxins produced by indoor mold may cause health problems. However, all indoor mold growth is potentially harmful and should be removed promptly, no matter what types of mold is present or whether it can produce toxins.

How do I tell if I have a mold problem?
The most practical way to find a mold problem is by using your eyes to look for mold growth and by using your nose to locate the source of a suspicious odor. If you see mold or if there is an earthy or musty smell, you should assume a mold problem exists. Other clues are signs of excess moisture or the worsening of allergy-like symptoms.

  • Look for visible mold growth (may appear cottony, velvety, granular, or leathery and have varied colors of white, gray, brown, black, yellow, green). Mold often appears as discoloration, staining, or fuzzy growth on the surface of building materials or furnishings. 
  • Search areas with noticeable mold odors.
  • Look for signs of excess moisture or water damage. Look for water leaks, standing water, water stains, condensation problems. For example, do you see any watermarks or discoloration on walls, ceilings, carpet, woodwork or other building materials?
  • Search behind and underneath materials (carpet and pad, wallpaper, vinyl flooring, sink cabinets), furniture, or stored items (especially things placed near outside walls or on cold floors). Sometimes destructive techniques may be needed to inspect and clean enclosed spaces where mold and moisture are hidden; for example, opening up a wall cavity.

Should I test for mold?

Sometimes, mold growth is hidden and difficult to locate. In such cases, a combination of air (outdoor and indoor air samples) and physical samples may help determine the extent of contamination and where cleaning or remediation is needed.  

For more information about mold, go to https://www.epa.gov/mold.