Mold Overview

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 spider populations.

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 Mold Testing.