While some scientists spend their lives studying the rainforest or the ocean, Jessica Green considers ecosystems closer to home: offices, classrooms and even bathrooms. A biodiversity scientist and director of the
I spoke recently with Green about bio-informed design, creating objects based on microbes and combatting hospital-acquired infections. Below are excerpts from our interview.
We think of ecosystems as a rainforest or the ocean. But you study the ecosystems in office buildings and even bathrooms. Why should we care about them?
One of the most interesting aspects of this emerging field is thinking about buildings and rooms within buildings as ecosystems. We've been spending hundreds of years trying to understand biological diversity outdoors. But in the place where we spend 90 percent of our lives -- indoors -- there's as great a diversity as you would see in a tropical rainforest. There are bacteria, fungi and viruses. These are all organisms that are interacting with one another, competing with one another, and we can't see them.
It's important to understand indoor ecosystems because they're our primary habitat. They're where we're picking up some of the microbes that live in and on us. Humans are also walking ecosystems. We have microbes in our body and on our body. We don't fully understand yet where we get most of our microbes, but it's reasonable to assume we get a lot of them from buildings because we spend so much time in buildings. We know the microbes in and on our body are important to our health. If we can understand the ecosystems in our primary habitat, that's one way of thinking about our health.
In recent work, you studied the microbial ecosystems in an office building. How did you go about that and what did you find?
This is the second major study that we did at the Biology and the Built Environment Center. It was on campus the University of Oregon. The building that we studied was called the Lillis Business Complex. We thought it would be a rich environment to study because it has offices, classrooms and restrooms. You have a variety of space types. We're interested in understanding how the number of people and the movement of people inside large buildings impacts microbial ecosystems. Because it's used for instruction and teaching classes, there are a lot of variations in the rooms in terms of the number of people in those spaces.
We studied that building in three different ways:
- We wanted to have an entire building scale view. There are more than 300 rooms in that building complex. Dust gives you something like an archeological record of what's going on in the built environment. We used a vacuum cleaner and sampled dust in every room. We did that to answer questions about how the form and organization of spaces in buildings is influencing what types of microbes live where. We first wanted to ask the basic question of whether you have different ecosystems in different space types. When an architect or an engineer is asked to design a building, the first question they are tasked with is how is that building going to be used?
- The second question related to the way rooms are organized within a building. Just like in a tropical rainforest, we know pieces of land that are close to one another have more species in common than pieces of land that are far apart. Would we see that in rooms clustered together on the same air handling unit or rooms close in terms of the walking path? We saw that in this building. We wanted to study the air and microbes inhabiting the building. You would expect the relationship between what's going on outdoors and indoors could be potentially fluid in terms of the air. We focused just on classrooms. We took air samples for about a week to ask basic questions like whether the indoor environment varied in a cyclic pattern. We were interested in the relationship between indoor air and outdoor air over time and how this was impacted by a specific design choice. We found it does [vary in a cyclic pattern], except only when you operate those rooms in a sustainable way where they are getting air directly from outdoors. In this building, they don't have windows. They have something called louvers. They're little metal grates you can open up to the outside. If you close those louvers and run the mechanical ventilation system, you don't see that cyclic pattern. There's a great lag in the relationship between indoors and outdoors. If you kept those louvers closed and used the mechanical ventilation system, you had an airborne fingerprint that was more similar to what was left behind by students in those classrooms.
- We did a detailed study in one particular room where we sampled surfaces. We wanted to understand a single room like a tropical rainforest and understand whether a desk is a different habitat than the floor or the wall. It is, but it's shared. We did find it's different. You can think of these different surfaces in a room as being different habitats.
What information did the study give you that helps you think about how this relates to human health?
We're still in the information-gathering phase of understanding the connection between design and how design impacts what ecosystems you get. The next phase of our research -- and what I think is important - is two lines of evidence. I see research in the built environment and on humans, these two kinds of ecosystems. They need to work together in parallel. They're going to inform one another.
We need to understand better how we're picking up microbes indoors and whether it's a lasting effect. If you go into a building, we don't understand how many microbes you're picking up from that building and where they're going. Are they just going onto your skin? Are they somehow making it into your digestive tract? We don't understand how our personal ecosystems are being colonized by the built environment. The second line of evidence is this research area of understanding the human ecosystem. We're in the beginning phases of understanding how our own personal biological diversity relates to our health. Most of what we know is based on research on the gut. This is an emerging research area.
So you'll be focusing some research on studying people?
We're starting to do those experiences in a controlled way. We're putting people into what's called a climate chamber. [A climate chamber is used to test products which either affect human comfort or whose performance depends on environmental conditions. The temperature of the air and of individual surfaces, air velocity and relative humidity can be controlled inside the climate chamber.] Climate chambers have been designed by architects to understand how altering the environmental conditions in a space influence a human being's perception of their personal comfort. We're starting to study the human microbial cloud. What is a person getting from the built environment? The next step is what the built environment is contributing to a human. We're starting to do that work.
You think we should design for better microbial ecosystems. What would a healthy building look like? Are we depending too much on mechanical ventilation and not spending enough time with windows open?
I want to be cautious because that's a new area. We've conducted one study in a hospital environment. The study demonstrated that in this one environment in Portland, a very green place, if you open windows in outpatient rooms, you get microbes in those rooms commonly found on plant leaves and in the soil. If you close the windows and run the mechanical ventilation system, in the air you tend to have more microbes commonly found on the human skin and in the human mouth. If you look at how evolutionarily related DNA sequences from the air and bacteria are to known pathogens, the proportion of sequences more closely related to pathogens is greater when you have the windows closed and the mechanical ventilation system on. But this is just one study in Portland. If you're in a more polluted city, we don't know the tradeoffs between running a mechanical ventilation system versus keeping the windows opened.
Right now, building code is centered on this concept of keeping the outdoors out. It's not possible to keep microbes outdoors. Microbes are going to colonize spaces. If you're not letting outdoor microbes inside, then the indoors is going to be colonized by people. Those microbes are going to be reproducing and populating the space. The concept of keeping microbes out is outdated. The new way of thinking is: We know there are going to be microbes colonizing the indoor environment, unless you're in a controlled environment like an operating room. If the indoor environment is going to be colonized by microbes, what kind of microbes do we want to be colonized with? Designers are going to start thinking about using this ecological framework versus trying to keep the outdoors out.
You argue that smarter building design could help us solve some of our most challenging problems, like hospital-acquired infections. How?
We know microbes play by similar ecological rules that plants and animals play by. There are some differences, but a lot of the mechanisms that shape biological diversity for plants and animals are similar to what we see for microbes. If we're going to try to tackle problems like hospital-acquired infections, thinking about pathogens in the context of the entire ecosystem that they're embedded in should be helpful. If you have a weed in your garden, you wouldn't just blowtorch the entire garden. If you did, that space is going to get colonized by more organisms and probably invasive, weedy ones. You want to promote the growth of plants you want to have around and minimize the growth of plants you don't want to have around. I think people who have a strong background in ecology, and in particular microbial ecology, would probably be a useful asset to people thinking about how to mitigate the risk of hospital-acquired infections.
Aside from architecture, what are other ways we could better design objects based on microbes?
I have not started research in this area, but I want to. It seems like such an obvious low-hanging piece of fruit for companies that are manufacturing furniture or personal devices like cell phones and computers. We know different types of materials are going to attract the growth of different types of microbes. In the health care industry, there's a lot of thought into whether the clothes they wear could be more likely to pick up and retain pathogens. Studying how materials tend to colonize entire ecosystems is fascinating to me. It could be really important.
Is anyone else doing this conscious approach to design, which you call bio-informed design?
The Alfred P. Sloan Foundation is the reason I got into this field. They put a significant amount of funding toward kickstarting this field of thinking about the biology of the built environment. There are a lot of research groups funded by the foundation in this area. One of the major strengths we have at the Biology and the Built Environment Center is a team of designers and biologists. Having that close collaboration between people who have never thought about design with people who have never thought about biology changed the way I think about my work. This coupling of designers and biologists is pretty unique. But that's changing because the foundation has proactively invested in this area. Their program is called the Microbiology of the Built Environment.
What's next for you and this work?
What we've all been doing in this field so far has largely been about answering the question: Are buildings ecosystems? People are agreeing that they are. Now that we convinced ourselves of that, the next step is to understand this from a mechanistic, more experimentally driven approach. What's causing these different microbial ecosystems to form in different buildings and spaces in buildings? What are the consequences of that? We need to understand better how as humans we're picking up microbes from buildings and whether or not that matters to our health.
There's been a lot of progress in sustainable design. The architects we're working with are committed to designing buildings so they have the lowest carbon footprint. Now they're thinking along this new dimension. Is it possible to consider two variables at once when you're designing, having a low carbon footprint and having a low health impact footprint?
Photo: Jessica Green