What is mold?
Mold is a kind of fungus related to mushrooms and yeast. It does not produce a mushroom stage.
Mold feeds by extending root-like branches into the substance on which it grows. Growth requires
moisture and organic nutrients but not light. Most molds reproduce by releasing microscopic
seed-like spores into the air.
When & where does it grow indoors?
In the indoor environment it may be found growing on the paper surfaces of sheetrock, on wood,
food, or any other organic material. It will not grow on clean non-organic materials such as
glass, metal or mineral surfaces. Mold growth is encouraged by warm temperatures and elevated
moisture levels (at or above 40%) in the air.
What are the consequences of living with indoor mold?
Some people have allergic reactions to certain kinds of molds when airborne spores are inhaled.
Respiratory allergies to mold spores may range from mild to severe. Mold growth indicates elevated
moisture in the air. Elevated indoor humidity has been correlated with increased risk of allergies
and asthma, likely due to the combined effects of increases in mold, bacteria, insect, mite and
How do I test for mold?
Mold testing by direct sampling of visible suspected mold growth can be done by the homeowner.
NEL provides tape lift kits that allow samples to be taken by touching suspected growth with
transparent tape that can be examined microscopically in the laboratory. Testing for the presence
of airborne spores is done by certified mold inspectors trained in the use of spore trap and
vacuum pump techniques. Spore trap testing allows for quantitative measures of the number of
spores in a given volume of air.
How do I evaluate test results?
Results of tape lift testing will confirm or refute the suspected presence of mold at a particular
location. Laboratory analysis normally provides identification of the type of mold (at the genus
level) and its abundance at the tested location. If mold is present, steps should be taken to
clean the affected area and eliminate the source of moisture causing the growth. In cases of heavy
contamination professional help may be required. Quantitative results from spore trap testing of
indoor air should be discussed with the licensed mold inspector who conducted the test. There are
no agreed upon national standards for safe levels of indoor mold spores and interpretation of
test results depends upon the protocol establish by the inspector. For more on indoor air testing
and the interpretation of results see the Maine Indoor Air Quality Council Guidelines on Mold and