One of the most common questions homeowners have is "How do I test for mold?" Most experts will discourage you from testing for mold because it is usually not necessary to identify the specific mold, and tests can be quite costly. Testing to determine the kinds and amounts of mold present is rarely helpful. No single test for mold can detect all types of mold, and the results can only estimate the amount of mold present, and only for the time the sample was taken. Problems can also occur in the interpretation of the results, and findings may produce false negative results. Additionally, test results are not predictive of health risks.

To date neither the Environmental Protection Agency (EPA) nor any other federal agency have set limits for mold or mold spores so there is no way to determine a "safe" level of mold in the home since molds can be found everywhere indoors and out.

What is sometimes done is to compare the indoor level of one type of mold species against the same specie outdoors. That may be an indicator of higher mold growth in the home.

If you decide to pay for environmental sampling of molds, before the work starts, ask those doing the work to establish the criteria for interpreting the test results. They should tell you in advance what they will do or what recommendations they will make based on the sampling results. The results of samples taken in your unique situation cannot be interpreted without physical inspection of the contaminated area, or without considering the building’s characteristics and the factor that led to the present condition.

The best way to detect mold in the home is by seeing or smelling it. Look for areas where mold may be visible. Mold may be any color: black, white, red, orange, yellow, blue or violet. Also look for discoloration of building materials where previous water damage may have occurred, such as drywall or plywood.

Another way to identify the presence of mold is through the odor associated with it. A musty or earthy smell often indicates the presence of molds. If you have ever walked into a closed up home or entered an old building, you may have smelled mold. Sometimes your nose tightens up, or you might even get a headache. Locate where the odor is most intense to see if you can see mold growing. Since the sense of smell decreases rapidly, it is best to smell for mold after being away for awhile.

Mold is easy to detect. If you can see it or smell it, you have mold. It can usually be detected by a musty odor. Often people say "My basement smells musty." That is a signal that there is mold growing in that basement. Mold comes in many different colors. It can be white, green, pink, brown, orange, or black. The color is not by itself , an indicator of toxic mold.

When people are talking about toxic mold, they are talking about Stachybotrys chartarum (also known as Stachybotrys atra) pronounced stack-ee-bought-riss.

It is a type of mold that is blackish or greenish black in appearance. Not all mold that is black is Stachybotrys. The black mold found on bathroom tiles is not Stachybotrys. Stachybotrys may occur when there has been excessive long-term water damage. Health effects of exposure to this mold are similar to exposure of other molds but may include inability to concentrate and fatigue. Usually these symtoms dissapear after the contamination is removed.

Controlling Molds and Mildew E332 — University of Wisconsin
Should you test for mold? Approaches to mold testing.
Do you still want your home tested?

EPA Mold Resources
Federal recommendations about testing for mold.

EPA A Brief Guide to Mold, Moisture and Your Home
Mold basics, clean up guidelines, and hidden mold. Sampling or testing for mold.

Minnesota Department of Health
Reasons why not to test. Links to pdf files.

Should You Test for Mold?

Frequently asked Questions


Mold in the Home