Letting the right microbes into your house is healthy

Instead of making our living environments as sterile as possible, we should be designing our homes for us and our microbial roommates.

pecciaYou have millions of roommates you’ve never met: microbial organisms inhabiting your home. Many of us would rather not think about the bacteria and fungi we cohabitate with, but two Yale engineers are making the case for building our homes with them in mind. Their article, appearing in Trends in Microbiology, highlights the need to better understand microbial ecology and how we benefit from it. Lead author Jordan Peccia is a professor of chemical and environmental engineering. We asked him what we can do to improve the microbial diversity of our living spaces.

ResearchGate: Many people think of bacteria, fungi, and other microbes as health hazards they need to rid from their homes. What’s wrong with this way of thinking?

Jordan Peccia: A very small fraction of the microbes that people are exposed to are hazardous to our health, most indoor microbes likely have little effect on humans, and some microbes are beneficial. Any approach that sterilizes your home, gets rid of the bad and the good.

RG:  What are some examples of ways we benefit from good microbes? What happens if we don’t get enough exposure to them?

Peccia: The microbes on us and in us are important to our physical and perhaps mental health. Beyond helping to digest food, some microbes help to train our immune systems, others reduce inflammation. The lack of early life exposure to some groups of microbes are associated with the development of allergies and asthma.

RG:  How much do we know about which microbes are good for us and which are bad?

Peccia: We know a lot about microbes that are infectious and allergenic; science has well-developed approaches for determining what is making a person sick. Not so for determining what makes us well. Newer DNA sequencing approaches are just now starting to associated the presence or absence of specific microbes with human health outcomes. The mechanisms are not fully understood.

RG:  What can people do now to make their homes good microbial environments?

Peccia: Removing the bad microbes is more straightforward. Ventilate with outdoor air, keep surfaces clean, and reduce the use of flooring materials, such as carpet, which contribute to a greater resuspension of house dust microbes into indoor air. If asthma triggers and allergies are a concern, some type of filtration of the outdoor or indoor air may be necessary.

Research on beneficial microbes in buildings is in a nascent stage, thus, I’m tempted to not make recommendations. However, there is some emerging information. Increasing the diversity—that is the number different microbial species—appears to be important, and increased diversity has been associated with living in rural areas and living with animals. From studies of the Amish in the US and Bavarian farmers in Europe, we know that early life exposure to microbes from livestock is associated with very low asthma and allergy rates. No need to move to a farm, this effect is also observed in dog owners in the US.

RG:  If you were building a house or apartment from scratch, what features would you consider to promote healthy microbial exposure?

Peccia: I’d build the house in an area with good outdoor air quality, actively ventilate the building—most homes are ventilated by leakage—and recover the heat so energy costs don’t rise. And, of course, get a dog.

Want to learn more about microbes in the home? Here’s some suggested reading:

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Featured image courtesy of Laura D'Alessandro.