Mould Testing

Mould belongs to the fungus family. Moulds are fungi with multi-cellular filaments called hyphae that we see growing on spoiled food or damp surfaces. In contrast, single-celled fungi are usually called yeast. Moulds are typically defined by the shape of their spores.

Moulds are prevalent in the air especially in humid conditions. Some people are not affected by them, or not aware if moulds are having any impact on their well-being. Those who are more sensitive to mould exposure can develop allergies or experience irritation in the eyes, skin, nose, throat and lungs.

Moulds thrive on moisture. Once they land on a damp spot in the home, they grow and reproduce by releasing tiny spores that float in the air. Walls, floors, carpets and furniture all provide the food that mould needs to grow. Reducing moisture is the best way to prevent or control mould growth. But first it is helpful to assess the mouldiness of our homes.

There are various mould tests providing different types of information. To assess the mouldiness of your home, we use the Mycometer-Air test because it provides the most comprehensive data on different kinds of moulds and mould components. This is important because mould typically consists of 0 - 5% spores, and about 95% hyphae by mass. Since health issues can arise from exposure to both spores and hyphal fragments, it is useful to measure both. In addition, some moulds produce mycotoxins that cause neurological disorders and these mycotoxins can be attached to any part of the mould.

The Mycometer-Air test samples all mould components by measuring the activity of the enzyme NAHA (N-Acetylhexosaminidase) that occurs in all mould parts. The result of a Mycometer-Air test thus indicates the reservoir level of mould in a home, and provides a useful basis for assessing potential health risks.

The Mycometer-Air test is one of the few mould tests that is globally standardised, making it highly reproducible and useful to compare two different sites, or to compare the same site at different times to track changes of indoor air quality. This reproducibility is one reason why the Mycometer-Air is the only test accepted for measuring mould in air for the 2011 Danish Standard DS3033 "Classification of the quality of the indoor climate in residential houses, schools, children’s day-care centres and offices”.

The Mycometer-Air sample is taken after disturbing the room air for 2 minutes with a standard air blower (called aggressive sampling). The air sample begins 2 minutes after the air blowing has stopped. This is critically important because the abundance of mould in an air sample can differ greatly depending on whether spores and mould fragments are suspended or not. For example some heavier spores like Stachybotrys settle more quickly to the floor compared to Aspergillus. The Mycometer-Air sampling procedure uses a standardised sampling height and standardisded air flow rate which are both factors that can change mould testing results.

Compared to other kinds of mould testing, the Mycometer-Air test often ends up being a faster, cheaper and more reproducible way to assess how much mould you are being exposed to at home, and therefore a more direct way to identify solutions. Our priority is to help you identify as quickly as possible if you should be controlling indoor humidity, or fixing water damage, or both. Reducing indoor humidity is the single most effective strategy to controlling indoor mould growth, and the earlier this is done, the sooner health issues may be resolved. 

To identify sources of mould growth, we sometimes use the Mycometer-Surface test to measure mould growth inside air conditioners or on water damaged walls. However a surface mould test does not measure the mouldiness of your home because it does not sample the air, which is the main route of mould exposure to your body. A surface mould test only helps identify possible mould sources.

Testing mould in your home to the species level, or testing your home for the presence of mycotoxins, gives you more information about what mould components you may be exposed to. 

This can be most relevant if you are working with a therapist to resolve mould infection issues. However, if your question is “do I need to control humidity to reduce exposure to indoor mould?” or “has this action reduced my exposure to indoor mould?” then we recommend doing Mycometer-Air tests. 
There are other mould tests available. They include:

1. Culturable testing:  Only viable spores on the right growth medium will grow. Multiple samples need to be taken on different culture media to increase the chance of culturing all the viable spores present. Many spores are non-viable, and will not culture. Therefore the chance of a false negative (meaning not finding a mould when it is actually present) is high with this technique.
2. DNA testing: DNA testing for mould is also known as QPCR (Quantitative Polymerase Chain Reaction) testing. This can give accurate results to the species level. One disadvantage of QPCR testing is its relatively high cost. 
3. Impact slides: This technique catches mould particles for identification under the microscope. Due to the similarity of many moulds, this approach can identify to the genus level. The accuracy depends on the skill of the analyst and is complicated by having different parts of different moulds mixed together.
4. Mycotoxin testing: Mycotoxins such as trichothecenes, aflatoxins and ochratoxins can be measured by the immuno-assay testing method. Since these natural toxins can be long-lived and carried on all types of mould fragments, they may be present in the home and in clothing long after the source mould is gone. The main disadvantage of this test is its relatively high cost.