How to Properly Collect an ERMI Sample
Intro
ERMI testing is controversial for a couple of reasons. Misunderstandings about its designed use case, inconsistent sample collection, and misuse of the test in general all have led to a general frustration in the industry by professionals and homeowners alike. In this sampling informational series our goal is to address some of the common issues with ERMI sampling and provide straightforward instructions for properly conducting an ERMI evaluation. Today we will be looking at how to properly conduct sample collection so that we can ensure that sample results are accurate, relevant, and helpful.
It’s helpful (essential) to understand that the ERMI test was designed for a very specific purpose, using very specific metrics. The ERMI test was developed to help researchers compare and establish a baseline for mold levels in homes across the country. To keep results cohesive for comparison, it was important to keep sampling procedures consistent and accurate. Using these metrics, they were able to establish a representative baseline for homes across the United States and establish a scoring or ranking system based on the samples collected. It’s also important to note that although peer-reviewed for research purposes, it has not been accepted by the EPA as an acceptable metric for evaluating homes.
Sampling Procedures
Mark off a 2m2 rectangle in both the living room and master bedroom.
Fit a standard household vacuum with a dust collection cassette from Mitest™ or DustChek™ or other acceptable sample collection agency.
Set timer for 5min and begin vacuuming the marked off rectangle starting at one end and making slow, sweeping, overlapping passes until you reach the opposite end of the rectangle. Continue the sweeping passes from end to end until the end of the 5min.
Place the caps on the sample cassettes and mark with location.
Repeat for 2nd location.
Both samples should be marked with their respective locations and appropriate information filled out on the laboratory COC.
Ship samples to lab of your choice and await results.
Some laboratories offer ERMI analysis on samples collected using a Swiffer cloth. It’s important to note although the same analysis can be done on these samples, the scoring system needs to be taken with a grain of salt. Because the Swiffer test allows you to wipe multiple surfaces in multiple areas of the home, you are no longer using the same comparison standards.
Although the original test was not designed for this methodology, it can still be helpful to analyze what kinds of mold are present on surfaces throughout the home. In this case you want to pay more attention to specie types that are present rather than focus on the numerical score that is given.
A couple of tips for collecting a useful sample using the Swiffer method:
Don’t collect directly from visible mold that is present. Tape lifts or other surface analysis are better suited for this purpose. If you wipe a bunch of mold from your windowsill and get a high ERMI score it isn’t really indicative of the mold load of your home, but rather just the windows you collected the sample from. The purpose of the Swiffer/ERMI test in general is to determine the mold load in settled dust and potentially unknown areas rather than direct mold evaluation.
Wipe only one direction with clean sweeping wiping motions. This helps keep the collection sample readable.
Avoid areas of super high dust as the background debris can interfere with the sample reading.
Avoid cross contaminating the Swiffer wipe to ensure the results are an accurate representation for your home.
