ERMI

What it means

ERMI stands for Environmental Relative Moldiness Index. EPA developed it as a tool for researchers to gauge mold contamination, including the amount of mold and some of the types present. EPA uses it to help characterize relative levels of mold in homes and other buildings and to study possible links with health effects.

EPA is explicit about its limits. The method “has been peer reviewed for research purposes,” but “has not been validated for non-research purposes.”

Why it matters to your bill

Some inspectors and mail-in labs sell ERMI tests to homeowners. Before paying for one, know what it can and cannot tell you. It is not an EPA-approved way to decide whether your home is safe, whether remediation is needed, or whether a job passed. CDC does not recommend routine mold testing, and EPA says that if visible mold growth is present, sampling is usually unnecessary. A visual inspection, moisture readings and a clear fix for the water source usually matter more. If you are deciding whether any test is worth it, see our page on mold test kits and our mold inspection cost page.