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Greener Architecture, Greater Indoor Pollution? How the Indoor Microbiome Affects Your Health

Greener Architecture, Greater Indoor Pollution? How the Indoor Microbiome Affects Your Health

You would never intentionally drink contaminated water, and no matter what your diet's like, you would never knowingly eat food that you knew could hurt you. And you certainly wouldn't let your children or pets play around with hazardous materials.

We pay so much attention to what we eat, drink, and surround ourselves with, but science is showing that we might need to start paying more attention to the impact of the quality of the air we breathe. And not just the air on the outside, the air on the inside, too. Research into the indoor microbiome is showing that the air in our homes and buildings is quite likely impacting our microbial health.1

What's the Indoor Microbiome––and Why Does It Matter?

The indoor microbiome is the ecosystem of bacteria that exists inside indoor spaces, including everything from homes and office buildings to airplanes and hospitals. While we've tended to think of indoor bacteria primarily in terms of cleaning, the indoor microbiome actually plays a big role in how you feel.

And this makes sense: after all, Americans spend an average of 90% of their time indoors, and as humans we breathe in and out 10,000 and 70,000 liters of air a day, all filled with microbes, chemicals, fungi, and all kinds of other things. All of this time working indoors means that we're spending most of our time breathing in whatever happens to be in the particular microbiome of that indoor environment. This can be a good thing or a bad thing, depending on the particular microbiome.2

Just as the human microbiome is unique to each person, the indoor microbiome of different spaces is unique to each space. While your microbiome is affected by what you eat, how you exercise, and your exposure to friendly flora, indoor microbiomes are affected by how the space is used, the people and pets in the space, whether or not it's ventilated so air from the outside can flow through, and of course, the quality of the outdoor air in the building’s vicinity.3,4

Here's the Problem:

Right now, most buildings are designed in ways that foster indoor microbiomes that are depleted and out of balance. One of the biggest reasons for this is changes in the way modern buildings are ventilated. You see, in an attempt to make buildings more energy-efficient, architects moved towards making them as air-tight as possible. While this does lower energy bills, the resulting decrease in ventilation creates a whole new level of indoor pollution coupled with reduction in our exposure to the health-supporting microbes present in nature.5

Before, air was able to move relatively freely between indoor and outdoor spaces, which meant that the indoor microbiome was constantly being replenished with bacteria from the outside. This kept it diverse and increased the chances of it staying balanced, which in turn helped our microbiomes stay balanced––because remember, we're breathing in all this "microbial soup" all day. Similarly, harmful chemicals, unfriendly bacteria, and Volatile Organic Compounds (VOCs from paint, carpet, air fresheners, and inhospitable microbes) were able to disperse.

However, since building design has changed and most buildings are no longer ventilated in the same way, the indoor microbiome doesn't get refreshed. Instead, harmful substances, inhospitable bacteria, and the VOCs they emit are all trapped together, creating a microbial mix that's out of balance and can negatively impact our health.

For instance, have you ever gotten lightheaded, had an upset stomach or a pounding head, or felt "off" after spending time in a new building? The indoor microbiome could be why: the compounds trapped in sealed buildings can quickly affect many different aspects of your health, from your breathing to the appearance of your skin.6, 7

And the effects don't stop after you leave the building. The changes that harmful compounds can make in your microbiome can have a subsequent effect on the rest of your body. When your microbiome is out of balance or depleted (which can happen from many things, including spending time in an unhealthy indoor microbiome), you're more likely to experience unwanted changes in your immune system, your breathing, and even your cognitive functioning!8,9,10

The good news is, it's absolutely possible to change the indoor microbiome.

Bacterial ecosystems are truly amazing in that, given a little help, they can eventually make a comeback from just about anything. And now that we're starting to get a sense of just how big an impact stagnant indoor microbiomes have on our health, architects and designers are starting to change the way they're designing buildings to foster healthy indoor ecosystems.11

One of the biggest shifts is in how we see the outdoors. Instead of something to keep out at all costs, we've started to understand how beneficial interaction with nature can be for our health and our lives. Studies show that buildings that are surrounded by parks or green spaces can have much healthier microbiomes, given adequate ventilation. This in turn benefits your microbiome, since you'll naturally start to pick up the beneficial airborne microbes that come in through the windows or ventilation system.12

There's also a new focus on environmental probiotics.

This is a new family of technology that uses the power of probiotics to replace the traditional cleaners and harsh, artificial scents that most air purifiers use. While many of them work just like a traditional air purifier by spraying substances into your air to deal with dust, pollen, pet dander, and unpleasant smells, these air purifiers use a special blend of probiotic bacteria.

When shot into the air in the form of a vapor, environmental probiotics help to naturally crowd out the bad guy bacteria that cause smells and health challenges, and even consume some of the irritants that negatively affect your microbiome.

Some types may even perform bioremediation on an environment––a process in which powerful probiotic bacteria actually break down the pollutants in stagnant or contaminated air and then replenish the indoor environment with beneficial bacteria, taking care of the issue and making it much less likely for it to reoccur all at once.

What can you do to support your environment, and in turn support your health?

While you won't have total control over all the indoor spaces you spend time in, you do have a lot of control over your home environment, which still makes up a big portion of where you spend your time. So try these three tips to make your home's indoor microbiome as gut-friendly as possible:

1. Focus on your air, not your hygiene.

At least not quite so much. Overcleaning (which to many of us just looks like “normal” cleaning) using harsh, artificial chemicals is really hard on your body and your home’s microbiome, and simply isn’t necessary for good hygiene. Plus, our overuse of antibacterial cleaning products is really counterproductive in the long term, since it creates the perfect conditions for inhospitable bacteria to get in and take over.

So ease off on the antibacterial cleaners and body washes, and focus on the quality of your air instead. Whether you do this through simple and natural home cleaning supplies, by opening up your windows and letting some of the benefits of nature get to work, or by switching out your normal air purifier for something more natural like essential oils, you’ll be doing your microbes a big favor––one that they’ll almost certainly return in the form of better health!

2. Spend some time outside.

While you can control what you bring into your home, you’re probably going to have to spend a lot of time in indoor environments where you can’t control the level of cleanliness or the quality of the air. To offset this effect, try getting outside into nature as much as you can. This will give you some great exposure to microbially-diverse air, get you away from industrial pollutants, and give you all the other health benefits of spending time in nature.

3. Consider getting a pet.

Pets are fantastic for diversifying your home’s microbiome, since they’re always running around outside and then tracking all kinds of interesting bacteria back in with them. If you already have a pet, then back off on the cleaning a little bit and let their wonderful microbiome get to work. Alternatively, if you don’t have the option to get a pet, see how you can spend more time with animals in general. Even something as relatively small as pet sitting or volunteering at a shelter can make a big difference to your microbiome (and you’ll feel great too.)

We're just starting to understand the true ramifications of an unhealthy indoor microbiome––but it's clear that the air we surround ourselves with is just as big a player in health as what we eat, drink, or put on our bodies.

So, support your indoor microbial community just as you would your own body’s microbiome; with just a few small changes, you can make a huge difference in this central component of your life and health.


1. Leung, M.Y.H. and Lee, P.K.H. (2016). The Roles of the Outdoors and Occupants in Contributing to a Potential Pan-microbiome of the Built Environment: a Review. Microbiome 4(21). doi: 10.1186/s40168-016-0165-2

2. Holmes, J.R. (1994). How Much Air Do We Breathe? Brief Reports to the Scientific and Technical Community 94(11).

3. Meadow​, J.F., Altrichter, A.E., Bateman, A.C., Stenson, J. . . .Bohannan, J.M. (2015) Humans Differ in Their Personal Microbial Cloud. PeerJ. doi: 10.7717/peerj.1258

4. Fujimura, K.E., Johnson, C.C., Ownby, D.R., Cox, M.J. . . . Lynch, S.V. (2010). Man's Best Friend? The Effect of Pet Ownership on House Dust Microbial Communities. The Journal of Allergy and Clinical Immunology 126(2). doi: 10.1016/j.jaci.2010.05.042

5. Kembel, S.W., Jones, E., Kline, K., Northcutt, D., Stenson, J. . . . Green, J.L. (2012). Architectural Design Influences the Diversity and Structure of the Built Environment Microbiome. The ISME Journal 6. doi:10.1038

6. Deng, W., Chai, Y., Lin, H., So, W.W.M., Ho, K.W.K., Tsui A.K.Y., Wong, R.K.S. (2016). Distribution of Bacteria in Inhalable Particles and its Implications for Health Risks in Kindergarten Children in Hong Kong. Atmospheric Environment 128. doi: 10.1016/j.atmosenv.2016.01.017

7. Norbäck, D., Hashim, J.H., Cai, G., Hashim, Z. Ali, F., Bloom, E., Larsson, L. (2016). Rhinitis, Ocular, Throat and Dermal Symptoms, Headache and Tiredness among Students in Schools from Johor Bahru, Malaysia: Associations with Fungal DNA and Mycotoxins in Classroom Dust. PLOSOne 11(2). doi: 10.1371/journal.pone.0147996

8. Jensen, G. S., Patterson, K. M., Barnes, J., Schauss, A. G., Beaman, R., Reeves, S. G., & Robinson, L. E. (2008). A Double-Blind Placebo-Controlled, Randomized Pilot Study: Consumption of a High-Metabolite Immunogen from Yeast Culture has Beneficial Effects on Erythrocyte Health and Mucosal Immune Protection in Healthy Subjects. The Open Nutrition Journal,2(1), 68-75.

9. Abreu, N. A., Nagalingam, N. A., Song, Y., Roediger, F. C., Pletcher, S. D., Goldberg, A. N., & Lynch, S. V. (2012). Sinus Microbiome Diversity Depletion and Corynebacterium tuberculostearicum Enrichment Mediates Rhinosinusitis. Science Translational Medicine, 4(151).

10. Liu, W., Chuang, H., Huang, Y., Wu, C., Chou, G., Wang, S., & Tsai, Y. (2016). Alteration of behavior and monoamine levels attributable to Lactobacillus plantarum PS128 in germ-free mice. Behavioural Brain Research, 298, 202-209.

11. Brown, G. Z., Kline, J., Mhuireach, G., Northcutt, D., & Stenson, J. (2016). Making microbiology of the built environment relevant to design. Microbiome,4(1). doi:10.1186/s40168-016-0152-7

12. Mhuireach, G., Johnson, B.R., Altricher, A., Ladau, J., Meadow, J.F., Pollard, K.S., Green, J.L. (2016). Urban Greenness Influences Airborne Bacterial Community Composition. Science of The Total Environment 571(15). doi: 10.1016/j.scitotenv.2016.07.037

13. EMLS Analytical. (2016). Indoor Allergen Analysis by ELISA for BetterAir.


Rachel Allen is a writer at Hyperbiotics who's absolutely obsessed with learning about how our bodies work. She's fascinated by the latest research on bacteria and the role they play in health, and loves to help others learn about how probiotics can help the body get back in balance. For more ideas on how you can benefit from the power of probiotics and live healthier days, be sure to subscribe to our newsletter. To learn more about how a healthy microbiome can enrich your life, subscribe to our newsletter.

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