New research uncovers an intriguing distinction in indoor fungi: daycares serve as hubs for yeasts, while private homes are more hospitable to molds. Could the people living within these spaces be influencing the microbial environments around them? A study titled “Yeasts Prefer Daycares and Molds Prefer Private Homes” explores this phenomenon.
Conducted by researchers from the University of Oslo in Norway, the findings were published in Microbial Ecology. The research involved dust samples collected from 123 daycares and 214 private houses across Norway during April and May to control for seasonal variations.
The study discovered that while private homes have higher fungal richness compared to outdoor settings, there’s no significant difference with regard to daycare centers. In terms of abundance, yeasts were found in greater numbers in daycares, whereas molds prevailed more frequently in private houses.
Almost half (49%) of the fungi detected indoors were shared between both environments; however, 31% were unique to daycares and 20% specific to homes. This suggests that while there are common fungal species found in various indoor settings, each environment fosters a distinct microbial community.
Microorganisms typically grow slower indoors due to reduced humidity and nutrient availability compared with outdoor conditions. Yet, certain fungi like molds and yeasts can adapt well to these challenging environments.
Toxins or volatiles released by these microorganisms may negatively impact the host’s immune system and cause health issues ranging from mild skin infections to serious fungal invasions. However, some studies suggest that exposure to yeast might offer protection against allergies and asthma in children.
Outdoor fungi can enter buildings through various means such as windows, doors, or ventilation systems. Their presence indoors increases during seasons when outdoor fungi are also actively sporing. To minimize seasonal effects, researchers collected all samples simultaneously across Norway.
In Norway, daycare attendees spend up to 70% of their time outdoors in summer and 31% in winter. This exposure brings more external materials into daycares, possibly fostering higher indoor fungal growth rates. Additionally, the lower number of occupants in private houses might reduce the risk of fungal transmission.
Another significant factor influencing fungal distribution is temporal usage patterns: daycares are occupied by many people for a few hours daily, whereas private homes are used over longer periods throughout each day.
The study also highlights that ventilation type—whether balanced, mechanical, or natural—is crucial in shaping indoor microbial communities. This variable ranks second only to building type and occupant density in significance.
Researchers recruited local inhabitants or daycare staff to collect dust samples for their analysis. They found a distinct seasonal pattern previously in two daycares: fungal richness was higher during summer and fall, emphasizing the importance of time variability in indoor microbial studies.
In conclusion, while molds are known health risks such as asthma triggers, this study does not directly correlate these fungi with adverse human health effects stemming from their presence in private homes versus yeasts’ dominance in daycares. Further research is needed to determine any potential impacts on human health from exposure to different indoor fungal compositions.
