Hold That Breath — Fungus Goes Airborne Easier Than We Thought
Add breathing in your house as another possible danger to your health. If your home is sick, it's possible you could get sick too.
The term "sick building syndrome" hit the airwaves years ago as a one size fits all reference to homes and buildings that are just too efficient — or too leaky — for their own good. It is a kitchen sink reference to properties that make inhabitants sick, for one unknown reason or another.
While many researchers studied the idea over the years, a recent study published in the journal Applied and Environmental Microbiology took a close look at the ease by which toxins from three different species of fungus become airborne under ordinary household conditions.
The Environmental Protection Agency (EPA) describes sick building syndrome as a situation "in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified."
In recent years, off-gassing of volatile compounds from newly laid carpet, appliances, adhesives, and more notably, poorly manufactured Chinese drywall have caused alarm among homeowners with homes that make them sick.
The new study looked specifically at fungi that could move from contaminated household surfaces into the air. Study authors wanted to know about air quality in homes with high moisture, or visible mold issues.
While fungi are common, some produce "mycotoxins," a substance created by the threadlike projections of fungi called "mycelia." Not all mycelium are created equal, with some producing harmful toxins, while others do not, or produce less.
The study looked at three particular fungi, Stachybotrys chartarum, Penicillium brevicompactum, and Aspergillus versicolor. All of these are common indoor molds can show up on gypsum or particle board, building materials, carpets, wall paper, and other household materials and furnishings.
By setting up an experimental bench and providing low-velocity airflow, researchers were able to determine if mycotoxins of the three species of fungi can become airborne and which are more likely to do so.
While it may seem that a small amount of mold, even unseen behind a bathroom mirror, is not a big deal, if dust or breeze can carry fungi elsewhere in the home — the mold playground gets larger.
In their study, researchers note that approximately 20% to 40% of buildings in North America and Europe have some form of "visible fungal growth." Using new wallpaper, scientists cultured the fungi on the paper and collected air samples as air flowed over the paper at different speeds. Their findings include:
- Each of the three fungi species readily reproduces on ordinary wallpaper, especially those with any kind of water damage.
- The mycotoxins of A. versicolor and P. brevicompactum are relatively light and became airborne at lower airspeeds, about the same rate as natural ventilation in common buildings.
- The velocity required by S. chartarum to disperse by air was slightly higher, but still within the type of ventilation that could be found in a normally maintained building.
In their paper, authors note "toxins were found also on particles smaller than spores, that could be easily inhaled by occupants and deeply penetrate into the respiratory tract."
These findings contribute to a growing body of knowledge about the indoor hygiene of the places we live. Homes with leaks, or in need of repair, could become fungal breeding grounds.
We demonstrated that mycotoxins could be transferred from a moldy material to air, under conditions that may be encountered in buildings. Thus, mycotoxins can be inhaled and should be investigated as parameters of indoor air quality, especially in homes with visible fungal contamination.
Bailey points out that while some energy efficient homes are sealed from the out-of-doors, "various water-using appliances such as coffee makers could lead to favorable conditions for fungal growth."
The study raises questions about how often aerosolized mycotoxins could cause an infection — and what would that infection look like? For now, the study is a heads-up on identifying mold problems in homes and buildings and the need to take appropriate steps to steer clear of spores that may be floating your way.