HERTSMI-2 (MSqPCR)

HERTSMI-2 Testing

Overview

HERTSMI-2 is a DNA-based MSqPCR test that analyses the dust sample provided for 5 particular moulds. These moulds are known as the “Big 5”. HERTSMI-2 is an acronym for Health Effects Roster of Type Specific Formers of Mycotoxins and Inflammagens – 2nd Version. The HERTSMI-2 score provides an indicator for people suffering from Chronic Inflammatory Response Syndrome or CIRS, as to whether or not it is safe for them to occupy their home without recurrence of symptoms.

How does HERTSMI-2 Differ from ERMI Testing ?

HERTSMI-2 differs from ERMI Testing in a few ways;

  • HERTSMI-2 Testing looks at 5 moulds, ERMI looks at 36 mould species.
  • The ERMI gives the result as a easy to understand comparison to an established database of water damaged buildings and non water damaged buildings.
  • As HERTSMI-2 Analyses for 5 moulds and is cheaper to do the analysis compared to 36 for the ERMI.

Which Mould Species are Identified in HERTSMI-2?

Aspergillus Penicilloides
Aspergillus Versicolor
Chaetomium Globosum
Stachybotrys Chartarum
Wallemia Sebi

How Can the HERTSMI-2 Score be Used ?

A HERTSMI-2 score <10 is indicative that the building is safe for re-occupancy.

The ERMI graph makes it possible to compare one house’s “mouldiness” with another without being a statistician.

This table assists with interpreting the graph:

Quartile Zone Percentage ERMI Value Relative Mouldiness
Q1 Green 25% of houses Between -10 to -4 Low Relative Mouldiness
Q2 Amber 25% of houses Between -4 to 0 Low to Medium
Q3 Amber 25% of houses Between 0 to 5 Medium to High
Q4 Red 25% of houses Between 5 to 20 High
Red Greater than 20 Very High

Mould Species Identification

One of the reasons why the ERMI has become such a powerful test for mould is that it also provides detailed information relating to the identification of species of mould present. Traditional methods of mould sampling, such as air sampling and microscopic  identification, fail to identify moulds to species because some species of mould have virtually identical spore structures often making it impossible to distinguish between them.

Why Species Identification is Important

Determining the species of mould can be helpful for a number of reasons. One of which being that certain moulds are associated with certain substrates. For example, Stachybotrys grows well on wet cellulasic material, so if it is present an assessor will look in the walls as Gyprock/drywall could be that source. Other species of mould are associated with flooring and carpeting so if certain types of mould are present they might indicate a problem behind carpet or other flooring.

From the perspective of the health of occupants, there are published relationships between certain mould species and deleterious health consequences.

Vacuum Sampling

NSJ Enviro offer two methods for collecting dust samples. The original ERMI process used vacuum dust sampling where a special nozzle is fitted to a vacuum cleaner and a sample of dust is taken by masking off a 900 x 1800mm rectangle in the occupants living room and a similar area in the master bedroom. They are each vacuumed for 5 minutes to obtain a composite sample. One clear advantage of this test is that the carpet acts as a repository for the mould spores to collect over time. An issue that also occurs is that when a home has been water damaged the carpet may have been removed. We have included a video on the product page that outlines the steps for vacuum sampling.

Swiffer Cloth Sampling

One clear limitation of ERMI vacuum sampling is that many homes do not have carpet, and many people who are susceptible to mould related illness have chosen to have wooden or tiled floors. As a result, the  was developed. It is important when sampling to collect enough dust for analysis, at least 5mg.

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