As a type of fungus, mold has a complex structure and biology. Many of the mold strains found in nature have some type of filamentous branching, or a thread-like structure known as hypha or hyphae in the plural. When you look at them closely, you will see these filaments are actually growing from fungal spores. This makes up a much greater aggregate form known as mycelium. In certain environments, such as forest soil these mycelium networks can be astonishingly expansive.

Though by the individual nature of their structure, hyphae are frequently fragmented into smaller pieces, which are often referred to as hyphal or fungal fragments. Many of which can become airborne when disturbed. These airborne hyphal fragments then act like bio-aerosols, which are miniscule particles that can settle almost anywhere. Including the human respiratory tract.

Where Are Hyphal Fragments Found?

Mold and other fungal spores exist everywhere in nature, and can easily find their way into human occupied interiors. That means that hyphae, and hyphal fragments can just as easily be found in indoor environments. They are increasingly likely in homes, buildings and structures that have recently suffered water damage.

In many of these cases, the presence of hyphal fragments is a clear indicator of fungal growth and can potentially cause allergies and other health issues. This is part of the reason why it is a good idea to have air sampling tests performed in any living quarters and areas suspected of mold contamination.

Air Sampling Testing For Hyphal Fragments

Air sample testing is often performed in homes, multi-family housing and commercial properties to assess the potential presence or severity of mold contamination in the indoor environment. This is often a wise step to take following a water intrusion event or at the conclusion of a water damage cleanup.

This involves air samples that are carefully collected from every room of note on the property. It typically includes basements and attics as well as other out of the way places where moisture or condensation can settle. In terms of liability issues, a control sample is also taken to assure the validity of the test.

Many times air sampling testing will be performed in the nearby outdoor environment. Ideally, the level of bioaerosol hyphae should be significantly lower in indoor samples than in outdoor samples. Just keep in mind that a lower level of fungal fragments in indoor samples doesn’t instantly exclude the possibility of active fungal growth.

When comparing outdoor and indoor air samples, other factors such as the season and the prevailing weather conditions need to be taken into account. The density of spores and hyphal fragments might significantly vary due to rain, evaporation, or above average ambient temperature.

Multiple Methods For Hyphal Fragment Testing

The most accurate testing analysis needs to sample multiple environments in at least two different ways. For any test to be considered thorough or complete it should incorporate both air and physical sample methods to ensure the most accurate and reliable overview of the fungal contamination.

With many of these testing scenarios the air is sampled via vacuum pumps that extract the air sample at a specific volume per minute. Each of these sophisticated vacuum pumps contains a chamber with a sticky surface where the particles are collected and deposited.

After the air sample is collected, the adhesive slide is removed from the vacuum pump and analyzed under a microscope to determine the total number of fungal particles. This can then be compared to other samples from related or dissimilar environments to gauge a baseline presence for fungi in the area. This information can then be compared with physical samples taken from any visibly affected surfaces.

When it comes to determining the exact species or strain of mold is growing in a contaminated area, a different set of discriminatory analyses needs to be applied. This often entails physically sampling viable fungal materials and then slowly germinating them under controlled conditions in a Petri dish.

Hyphal Fragments At Normal & Elevated Levels

All the vigor in these testing methods plays an important role in assessing what the natural fungal presence for an area is, and then whether or not the current fungal presence is elevated above normal levels through the density of airborne hyphal fragments.

In most of these instances, the acceptable levels of fungal spores and hyphal fragments can vary significantly based on the species of fungus in question. While also factoring in the outdoor weather conditions.

Normal levels are typically calculated based on the levels of fungal particles in outdoor samples. The fungal particles in indoor samples should be qualitatively equal or nearly equal to the particles in outdoor samples. In a case where the number of total particles is quantitatively lower in the indoor samples, it should be measured by a cubic meter.

Common Fungal Strains Found In Hyphal Fragment Air Tests

While there are technically tens of thousands of different fungal spores in nature, there are a few that tend to show up in hyphal fragment air tests. This includes Aspergillus and Penicillium stains, which are spores that are often grouped in total particle measurements due to their relative similarities as well as their overall regular presence in air.

Though the presence of some fungi in indoor samples, even in low volumes, can be concerning. This includes Stachybotrys, or so-called “Toxic Black Mold” and Chaetomium. Even a small volume of hyphal fragments from these strains is an indicator of a serious contamination. Especially when you consider that these mold strains are rarely present in outdoor samples.

Are Hyphal Fragments Considered Dangerous?

At this time, the specific relationship between hyphal fragments and the influence on respiratory illnesses is still being researched. Though a growing body of research suggests that exposure to a high volume of hyphal fragments can increase the severity of asthma symptoms and other chronic respiratory health conditions.

Even in otherwise healthy individuals, hyphal fragments, fungal spores and potentially dangerous mycotoxins can become trapped in the mucus in the nose and are easily expelled from the respiratory tract.

There are also some individuals who have a genetic predisposition to inflammatory conditions when exposed to mold spores and airborne mold contaminants. This can trigger an autoimmune response as well as increase the likelihood of other chronic inflammation symptoms.