Molds are microscopic organisms present everywhere, indoors and outdoors. To grow and develop, molds need moisture and an organic food source (e.g., wood, paper). Molds grow by digesting organic material, gradually destroying whatever surface they grow on. Visible mold growth varies in color, it can be green, gray, brown, or black. The problem isn’t just that molds grow on surfaces; it’s that molds release countless tiny spores, which travel through air.

Molds produce health effects via inflammation, allergy, or infection. Allergic reactions (e.g., hay fever) are common threats of mold exposure. Typical symptoms that mold-exposed persons report (alone or in combination) include respiratory problems (e.g., wheezing, difficulty breathing, shortness of breath), nasal and sinus congestion, eye irritation (burning, watery, or reddened eyes), hacking cough, nose or throat irritation, or skin rashes/irritation.

Most people test for mold when they smell an unusual odor, see discolored spots, or become sick for no apparent reason.  Because mold growth often is caused or accelerated by moisture, many people also test for mold after a significant water-related event such as heavy rains , water penetration in the basement, dishwasher floods the kitchen, washing machine floods in the laundry room, etc.