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The Microbiology of the Built Environment & Why This Matters to Your Health

Quick question: Do architects have anything in common with scientists? Nothing could seem as different a job as these two, right? Well, it turns out that the roles of an architect and more specifically, a microbiologist are more intertwined than we think!

Imagine how much time we spend in buildings, at home, at work, at school, supermarkets, libraries, cafes and much more. Now, who do you see around you in these buildings? People of course, and maybe animals, but there are also others invisible to our naked eye! These are ‘eensy-weensy’ microorganisms like bacteria, fungi and viruses present in our environment, on us and on animals, and collectively termed as microbiota. The genomes of the microbiota are called microbiome. The field of microbiology in the built environment is gaining popularity, as the trend of sustainable “bio-informed” buildings emerges.

A “bio-informed” building is a building design meant to optimise the microbial community within it to promote good health of its occupants. If you are viewing an apartment for lease, then good ventilation and a non-water-damaged environment are things you would naturally look out for. But, have you ever stopped to consider the logic behind this?

Indoor microbiota communities are established largely from the outdoors. Studies show that outdoor microbiota, at around two times higher concentrations than indoors, can flow in through open windows, unexpected slow leaks and tiny openings in buildings at close to 100%.

With good ventilation, there will be greater diversity of microbiota. Exposure to the right kinds of microbes has been shown to be beneficial to human health. Lower fungal diversity has been associated with increased asthma risk. In young children, exposure to high levels of allergens and some bacteria may be health-promoting, as these microbes colonise the gut to strengthen the immune system.

Sentinel microbes exist that allow scientists to easily monitor and quantify microbial growth, but the challenge for architects is to channel this beneficial microbiota, and filter harmful ones out. In water-logged areas due to flooding or high rainfall, these soaked surfaces are a haven for sprouting microbes. Architects can pre-empt for such situations using plumbing biofilms coated with counter microbes that germinate in wet conditions to neutralise the toxic microbes. Bullitt Centre in Seattle, WA, is currently the only office building awarded the ‘Living Building Challenge’ certification, designed to improve occupants’ heath.

Aside from architectural design, humans ourselves are a major contributor of microbial changes, as well as pets. We spend more than 90% of our time indoors, breathing in 16,000 litres of air daily. Inside, we are constantly immersed in the indoor air and re-suspended dust, and in contact with surfaces, other people and pets. Our skin microorganisms are like mini colonisers, where they deposit themselves in the room we walk into at a rate of 106/hour airborne microbial cells, forming their own microbial signatures. Our trail of microbes left behind acts like evidence that can be analysed to determine the plausible sources that the microbes came from. For instance, a pet-friendly office may show a microbe ratio of 40% humans : 30% outdoors : 30% dogs. Because of this continuous exchange and flow of microorganisms around us, people have started on ‘self-tracking’ – a phenomenon where they adorn wearable sensors to collect their personal biological, environmental, physical and psychological data to optimise a specific lifestyle for curing of diseases. Scientific validity of these experiments is still questionable as of now, and protocols would have to be put in place to standardise data.

As for your pet pooch, saliva and kisses are not the only thing Fido is planting on you. Early life pet exposure has been shown to have the ability to reduce obesity and allergic disease. Would not this little titbit have had been a useful persuading factor to get a pet as a kid? Oscillospira, a bacterium of of the Ruminococcaceae family is enriched in the gut microbiota of infants, where it associates with a leanness-promoting bacterium. Streptococcus levels are depleted, giving a possible decrease in cardiovascular risk in infants.

An it’s not just pets in the house that influence what your toddler or small child is breathing? Recent research shows that the very act of crawling indoors stirs of a characteristic dust cloud that is inhaled by the infant and that dust samples from the carpet are a poor representation of the microflora. This means that sampling of dust should occur in the breathing zone to properly assess what the infant is exposed to.

Our home environment is a lot more than the aesthetics of furniture and form and function, of bathrooms, and bedrooms. The hidden microscopic world shows a great interplay between the building structure and our human microbiota. Establishing the details of this relationship with the aim of improving our health outcomes will prove very useful even as world population density increases and the concrete city expands, and we are brought into even closer contact with our surroundings. The role of scientists that can practically act as healthy building consultants will continue to expand in order to translate scientific knowledge into bio-informed practices, and in turn, lead towards healthier homes.

References

Brown, G. Z., Kline, J., Mhuireach, G., Northcutt, D., & Stenson, J. (2016). Making microbiology of the built environment relevant to design. Microbiome, 4, 6. https://doi.org/10.1186/s40168-016-0152-7

Gimbert, C., & Lapointe, F. J. (2015). Self-tracking the microbiome: where do we go from here? Microbiome, 3(1), 70. https://doi.org/10.1186/s40168-015-0138-x

Hyytiäinen, H.K., Jayaprakash, B., Kirjavainen, P.V., Saari, S.E., Holopainen, R., Keskinen, J., Hämeri, K., Hyvärinen, A., Boor, B.E. and Täubel, M. (2018). Crawling-induced floor dust resuspension affects the microbiota of the infant breathing zone. Microbiome, 6: 25. https://doi.org/10.1186/s40168-018-0405-8

Peccia, J., & Kwan, S. E. (2016). Buildings, Beneficial Microbes, and Health. Trends in Microbiology. 24(8): 595-597. https://doi.org/10.1016/j.tim.2016.04.007

Prussin, A. J., & Marr, L. C. (2015). Sources of airborne microorganisms in the built environment. Microbiome, 3(1), 1–10. https://doi.org/10.1186/s40168-015-0144-z

Stephens, B. (2016). What Have We Learned about the Microbiomes of Indoor Environments? mSystems, 1(4), e00083-16. http://msystems.asm.org/content/1/4/e00083-16

Thaler, D. S. (2016). Toward a microbial Neolithic revolution in buildings. Microbiome, 4(1), 14. https://doi.org/10.1186/s40168-016-0157-2

Tong, X., Leung, M.H.Y., Wilkins. D. and Lee, P.K.H. (2017). City-scale distribution and dispersal routes of mycobiome in residences. Microbiome, 5:131. https://doi.org/10.1186/s40168-017-0346-7

Tun, H. M., et. al. (2017). Exposure to household furry pets influences the gut microbiota of infants at 3–4 months following various birth scenarios. Microbiome, 5(1), 40. https://doi.org/10.1186/s40168-017-0254-x

The Greenest Commercial Building In The World. http://www.bullittcenter.org/

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