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What is the best test to check the level of mold contamination in your home?

There are currently no officially recognized tests available. This gap prevents you from knowing the condition of the house you intend to live in. It would be much simpler if, when renting or buying a house, we could request a document indicating the level of mold contamination in the building. Similarly, when sending your child to school or daycare, it would be wonderful to know more about the quality of the environment they will be in. Unfortunately, experimental tests are currently in use, and there is no official registry for the toxicity levels of indoor spaces. If authorities finally acknowledged this danger and implemented standards, it could potentially lead to a significant reduction in healthcare costs. However, the reality is that hospitals and other government buildings would be the first to require repairs, including fixing partition wall Manchester, and our authorities, as you know, lack the funds for that.

In the United States, people have won lawsuits against property owners when their health has been affected by such conditions. However, in Canada, no such cases have resulted in compensation payouts. After all, the owners of these enclosed “aquarium-like” spaces where you can’t even open a window to ventilate the area are not poor individuals. Insurance companies also do not want to incur the costs and simply refuse to cover risks associated with poor indoor air quality and health issues.

Tests for Air Quality Assessment

However, tests do exist. They have been available for a long time; the only problem is that you won’t be able to use them as evidence in legal proceedings. So, if your goal is to seek compensation, it is currently unattainable in Canada. But if your goal is to assess the risk of health issues in a particular space and attempt to rectify the situation, please continue reading.


There are two tests that mold treatment specialists use to quantitatively assess the level of contamination in indoor spaces.

The first test is called ERMI (Environmental Relative Moldiness Index). It includes 36 species of mold, all of which are hazardous to health. These specific molds were selected for the test because they pose the highest health risks. It is recommended to conduct the ERMI test first. The test will indicate whether your environment is not too bad or whether you should contact specialists in CIRS treatment.

The second test is HERTSMI. It is recommended to use this test after the space has undergone remediation to assess the effectiveness of the cleanup which may have been done by professionals from HERTSMI includes some parameters from the ERMI test. Therefore, if you have the results from ERMI, you can calculate the HERTSMI value. HERTSMI focuses on the five most dangerous types of mold.

How the ERMI test works

ERMI is a DNA-based testing method that allows you to determine the amount of mold. Unlike mold traps, ERMI is made from a dust sample collected in several ways. The sample is analyzed by quantitative mold ERMI is a DNA-based testing method that determines the quantity of mold. Unlike mold traps, ERMI is performed using dust samples collected in various ways. The sample is then analyzed using Mold-Specific Quantitative Polymerase Chain Reaction (MSQPCR). ERMI analyzes settled dust in homes and buildings to determine the DNA concentration of different mold species.

What does the ERMI test assess?

The ERMI test does not determine whether the mold present is old or new; it simply measures the level of contamination in the space. Mold colonies may be invisible, but micro-particles enter the air and settle as dust.

It is this settled dust that is analyzed to determine the extent of contamination. There are several methods of collecting samples for testing, and we will focus on the one needed for treatment purposes. In other words, we just need to know the level of contamination in the space, whether a patient can recover in that environment, and if it doesn’t exacerbate their condition further.

Where is the mold located?

The ERMI test assesses mold levels over time, rather than providing an “instant snapshot” of the current mold spore situation in the house. It has multiple applications, including helping to determine if a house has had water damage in the past, leading to mold growth. You will find mold spores in the open areas (where you collect samples) even if you can’t visibly see the source of those spores. The test is performed first, and then the search begins for the specific mold that caused the unfavorable test result. However, even if you spot a visible mold spot, you don’t take a sample from it. You are interested in the areas where seemingly nothing is present, except for the dust that is your target when collecting the sample material.

What types of mold does the ERMI test check for?

Despite there being numerous types of mold, the ERMI test examines 36 species, which are divided into two groups. Group 1 consists of 26 mold species associated with water-damaged buildings, while Group 2 includes 10 common species not linked to water-damaged buildings and more likely to be found outdoors. For the sake of safety and structural integrity, buildings are required to undergo regular building wrap maintenance to ensure that the protective wraps and coverings remain in optimal condition. The groups identified by the ERMI test are as follows: [Note: I’ll provide the groups in English as the test terminology is generally in English.]

Group 1: Mould, water damaged

  • Aspergillus flavus/oryzae
  • Aspergillus fumigatus
  • Aspergillus niger
  • Aspergillus ochraceus
  • Aspergillus penicillioides
  • Aspergillus restrictus
  • Aspergillus sclerotiorum
  • Aspergillus sydowii
  • Aspergillus unguis
  • Aspergullus versicolor
  • Aureobasidium pullulans
  • Chaetomium globosum
  • Cladosporium spaerospermum
  • Eurotium (Asp.) amstelodami
  • Paecilomyces variotii
  • Penicillium brevicompactum
  • Penicillium corylophilum
  • Penicillium crustosum
  • Penicillium purpurogenum
  • Penicillium spinulosum
  • Penicillium variabile
  • Scopulariopsis brevicaulis/fusca
  • Scopulariopsis chartarum
  • Stachybotrys chartarum
  • Trichodermaviride
  • Wallemia sebi

Group 2: Common types of mold

  • Acremonium strictum
  • Alternaria alternata
  • Aspergillus ustus
  • Cladosporium cladosporioides 1
  • Cladosporium cladosporioides 2
  • Cladosporium herbarum
  • Epicoccum nigrum – if your test shows a high value for this type of mold, take your favourite potted flowers out of the house and test the room in six months.
  • Mucor amphibiorum
  • Penicillium chrysogenum
  • Rhizopus stolonifera

How to properly collect a sample using a cloth?

Using a wipe that closely resembles the wipes you buy for cleaning, you can collect dust samples following specific rules. You can use one side of the wipe or both sides. We need to collect samples in the rooms that we want to test. You can collect one sample for the entire house, or you can collect a sample for each room. We will collect one sample throughout the house. Follow the instructions for packaging and sealing the dust sample wipe, which were provided with the test kit.

It’s important to ensure an adequate amount of dust for successful laboratory analysis. This means choosing the right places to collect dust and gathering a sufficient quantity.

Rooms for sample collection:

These are the rooms where you spend a significant amount of time. Typically, this would be your bedroom and likely the living room. Then choose rooms that are slightly further away from these rooms. These will be two additional rooms. Now, here are some general guidelines for collecting dust:

  • Air filters can be good places to collect some dust.
  • Collect dust from surfaces that are not lower than 50 cm from the floor and surfaces closer to the ceiling.
  • Collect dust from smooth surfaces that won’t damage the wipe.
  • When collecting dust, wipe in one direction only.

Sample Collection Rules

Wear a pair of rubber gloves to avoid contaminating the sample. Open the wipe as wide as possible. Look carefully at the rooms you have chosen for dust sample collection. If you’re the type of person who wipes dust diligently several times a day, you may need to wait 2-3 weeks until enough dust accumulates to collect a sample.

However, often the ideal places for sample collection are not regularly wiped by people. These places include:

  • Ceiling fan blades
  • Upper edges of cabinet doors
  • Shelves inside cabinets and suspended shelves
  • Upper parts of door frames and picture frames
  • You can also take a sample from a dresser or small table.
  • Air vents, but only if you can collect dust that is not contaminated with debris.

Places where you should not collect dust samples:

  • Off the floor;
  • From areas where you see mold;
  • In the kitchen;
  • From the walls;
  • If you see parts of insects, there is no need to take a sample;
  • Near the front door (to the street or backyard);
  • Near the windows;
  • In the garage. You only check living rooms!
  • Along exterior doors, windows, or anything close to a street entrance. Because it can skew the results, we check your accommodation.

How to interpret the test result?

There is no clear boundary between a good and a bad result, but a score above 8 is usually considered harmful to health. However, what may be acceptable for some people may be unacceptable for others. Most people with Chronic Inflammatory Response Syndrome (CIRS) cannot tolerate an ERMI value above +2 as they already feel unwell. There are also many individuals who are even more sensitive, often requiring an ERMI score below -1. It is always important to listen to your own body, as you may have your own “safe” ERMI level.

How does HERTSMI-2 different from ERMI?

HERTSMI-2 is typically conducted after mold remediation has been performed. It includes five of the most dangerous mold species:

  • Aspergillus penicilloides
  • Aspergillus versicolor
  • Chaetomium globosum
  • Stachybotrys chartarum
  • Wallemia sebi

HERTSMI-2 score <10 indicates that the building is safe for occupancy under normal circumstances. If you have conducted an ERMI test, you can calculate the HERTSMI-2 score yourself. Its purpose is to save money as it is cheaper than ERMI.

Note the meaning of Stachybotrys chartarum. If you have found even one spore of this mold, some experts recommend simply leaving the house as soon as possible. For more information contact indoor environmental professionals from your area.

How to obtain the HERTSMI score from ERMI test?

You can determine the HERTSMI score from the ERMI report by reviewing the results for the five highly dangerous mold species. Find Aspergillus penicilloides, Aspergillus versicolor, Chaetomium globosum, Stachybotrys chartarum, and Wallemia sebi in your ERMI report and write down their values.

Sum up the scores to obtain the HERTSMI score from the ERMI report.

Add 10 points if:

  • Aspergillus penicilloides more than 500
  • Aspergillus versicolor more than 500
  • Chaetomium globosum over 125
  • Stachybotrys chartarum over 125
  • Wallemia sebi over 2500

Add 6 points if:

  • Aspergillus penicilloides more than 100
  • Aspergillus versicolor more than 100
  • Chaetomium globosum over 25
  • Stachybotrys chartarum over 25
  • Wallemia sebi more than 500

Add 4 points if:

  • Aspergillus penicilloides greater than or equal to 10
  • Aspergillus versicolor greater than or equal to 10
  • Chaetomium globosum greater than or equal to 5
  • Stachybotrys chartarum greater than or equal to 5
  • Wallemia sebi greater than or equal to 100

The obtained sum is the HERTSMI score, which can be interpreted as follows:

  • <11 It is safe to occupy the building
  • 11-15 Borderline – Clean and Retest
  • >15 Dangerous for people with CIRS (Chronic Inflammatory Response Syndrome)

Where to order an ERMI test kit?

You can order an ERMI test kit, which ships to Canada through the provided link. Perform the test and examine the results. If there is a statement in red letters recommending you to contact a doctor, it means that anyone living in such a house will experience health issues. The only difference is how quickly it will happen.


Can you have a high ERMI score simply because mold spores randomly entered your home? The answer is straightforward: if you followed the sampling instructions, no, it cannot happen. You collected dust that is scattered throughout the house but not near windows or doors, not in the kitchen, not in the garage, and not where you see the affected areas. If you had sampled those areas, then yes, the result could have been distorted.

Mold spores cannot simply enter your home and linger for years without doing anything. If you have mold in the ERMI test, and it is quite significant, chances are you have a mold problem somewhere.

Application: highly toxic molds (HERTSMI test)

  • Aspergillus penicilloides can be found in dried fruits, spices, paper archives, old furniture, carpets, household dust, and clothing. It is also associated with dust mites and known for its allergenic properties.
  • Aspergillus versicolor can be found in compost, peat, linoleum, particleboard, paintings, cheeses, spices, grain storage, household dust, and dusty mattresses. This species is highly toxic and can cause a musty odor indoors. A. versicolor is known to produce the carcinogen sterigmatocystin. It is an allergen, and its mycoses can cause osteomyelitis and infections of the ear canal, nails on hands and feet.
  • Chaetomium globosum is typically isolated from soil, decaying plants, seeds, foodstuffs, decaying wood, and marine deposits. In fact, C. globosum can be found on wallpapers in water-damaged homes. Sporulation of this fungus typically occurs more easily in dark conditions, and the resulting spores are highly resistant to drying. While not particularly allergenic on its own, its presence appears to enhance allergic reactions to other allergens (e.g., pollen). This species causes invasive lung infections, subcutaneous infections, and infections of the nails on hands and feet.
  • Stachybotrys chartarum – typical black mold. It is widespread worldwide, mainly found on decaying plant material. S. chartarum possesses a set of enzymes associated with plant degradation, making it potent in destroying all types of wood, paper, and natural fibers (e.g., wool). Therefore, it is often an indicator of moisture problems in homes and can grow on paper, wallpapers, wall panels, wood, and textiles. S. chartarum itself is not a common pathogen, but it draws special attention due to its role in Sick Building Syndrome development, thanks to high production of mycotoxins (satratoxins G and H). Prolonged exposure to such toxins can cause various illnesses, including nausea, dermatitis, rhinitis, depression, general malaise, headaches, sore throat, and more. S. chartarum is also known to invade lung tissue.
  • Wallemia sebi can be found growing on substrates that desiccate many other fungi. These substrates

You can read about the other mold species that are tested by the ERMI test here: ERMI Molds


Indoor Air Quality in Office Buildings: A Technical Guide

By E. Jane Sidnell and Owen D. Pawson, Miller Thomson, LLP March 1, 2003
Sick Building Syndrome