The EPA developed the ERMI mold test, then told consumers not to use it, but it remains the primary test used in litigation, real estate, and medical diagnosis

EPA researchers developed the Environmental Relative Moldiness Index (ERMI) as a research tool for large epidemiological studies. The EPA then explicitly stated that ERMI 'is not recommended for use except as a research tool' and 'is not recommended to make decisions about remediation or health care.' The EPA's own Office of Inspector General warned that ERMI has not been validated for public use and that companies were inappropriately advertising it while referencing the EPA. Despite all of this, ERMI is one of the most commonly ordered mold tests in the United States, used routinely in home sales, tenant disputes, mold litigation, and by physicians diagnosing Chronic Inflammatory Response Syndrome (CIRS). This matters because ERMI has significant methodological problems that make it unreliable for individual home assessments. Its composite dust sampling method cannot identify which room has a problem. The test's standard deviation of 3 is enormous given that 50% of all tested homes fall within an index range of -4 to 5 — meaning a single home could test as 'safe' one week and 'dangerous' the next due to normal statistical variation. Newer research has found no association between ERMI Group 1 molds and contemporaneous water damage, undermining the test's core premise. Yet homeowners are paying $300-$500 for this test and making $30,000+ remediation decisions based on its results. This paradox persists because there is a vacuum of better alternatives. The EPA will not endorse ERMI for consumer use but has not developed or endorsed any replacement test. Physicians treating mold illness need some quantitative measure and ERMI is the only one with a published, peer-reviewed index. Lawyers need a number to present to juries, and ERMI provides one with an EPA logo attached. The result is a test that the organization that created it says you should not use, being used to make the most expensive decisions homeowners face.