What is a normal indoor mold count?

A normal mold spore count in a room is usually 200 to 500 spores. It's normal and safe for there to be between 1 and 1500 mold spores in a room, as long as the mold colonies don't grow visibly and there's no water damage. Mold spores are present in virtually every room in every building. A common test plan for eliminating mold specifies that the indoor mold level or the spore count should not exceed 50% of the outdoor level.

This approach can be silly, especially in the mold sampling reports that I reviewed, in which the genera and species of indoor mold spores were completely different from those of outdoor mold spores. If the mold sample processing laboratory actually uses an expert to process the samples (rather, part-time, high-volume workers with minimal education), then the variability in laboratory results is much lower than the variation in mold sample results caused by variations in sampling conditions that we discuss later in Mold sampling conditions cause a large variation in results. Many states maintain mold information sites and have documents available that provide detailed information on how to clean and treat mold. Professional mold testing will identify the type of mold in your home, the level of infestation, and the next steps to take.

Mold levels are used to give us an indication of whether occupants are exposed to mold that originates from the indoor environment. A professional mold test usually begins when an inspector looks for signs of mold, such as water stains, musty smells, or visible mold growth. Keep in mind that only 10% of all molds that exist will grow on any crop, so your mold screening test is not 90% reliable when you open the package. There is mold everywhere, the question is whether the mold that exists rises beyond normal conditions.

Lizabelle, check out AEROSOLS, SEALANTS AND MOLD PAINTS (article link on the left). Nor would I rush to do anything drastic or expensive, but I would not just treat mold by aerial or superficial means; the right steps are 1.In addition to identifying the types of mold present, the test results will also give you an idea of the concentration of mold spores in the air. Unfortunately, mold reports are often used to sell unnecessary services based on misleading information, such as “high levels of mold” compared to those from outside. Stachybotrys are widely considered to be the most dangerous form of indoor mold and produce mycotoxins and must be eliminated.

Simple changes, such as relative humidity, as well as changes in the pattern of air movement in a building, cause major changes in the level of mold in the air, even when mold is found on exposed surfaces where it could reasonably be detected. The level of mold spores that appears in your report is quite high, much higher than what a normal source of mold in outdoor air would explain. As a result, it's often difficult to completely eliminate these molds from your home, as many times the mold species found outside the house are different from those found inside the house. Patrice, your indoor mold levels aren't unusual in a flooded building with a very problematic mold reservoir; I've seen even higher ones.

What's more, since Stachybotrys mold spores are large, warty black particles, they're easy to see on building surfaces and in a sample of mold on a surface, dust, vacuum, or air.

Cassie Ulery
Cassie Ulery

Wannabe internet aficionado. Hipster-friendly pop culture trailblazer. Certified internet aficionado. Extreme zombieaholic. Professional beeraholic. Total beer aficionado.