You can't always see mold even at high concentrations.
Mold and mold spores adversely affect indoor air quality (IAQ). In low levels, molds and mold spores are generally harmless but if their levels increase they can affect people; especially people with allergies, asthma and respiratory conditions or suppressed immune system. We air test for the type and concentration of mold spore. Mold is known as an indoor air pollutant, alongside carbon monoxide, asbestos, and cigarette smoke. According to the EPA, indoor air pollutants are known to cause irritation in the eyes, nose, and throat, in addition to headaches, dizziness, and fatigue.