ABSTRACT

Built environments are the structures that humans create to shelter from the outdoors and provide spaces for living, working, playing, and getting places. Along with humans, pets, pests, and house plants, built environments house a range of microbes. Preliminary studies indicate that indoor spaces have distinct microbial communities, influenced by building materials, ventilation and airflow, moisture, and human and animal activity. The Academy convened a colloquium on September 9, 2015 to examine the role of complex microbial ecosystems found in built environments, including their effects on building chemistry and human health. Studying the microbiology of built environments can change the ways we design, build, operate, occupy, and clean our indoor spaces.

Front Matter

The American Academy of Microbiology (Academy) is the honorific branch of the American Society for Microbiology (ASM), a non-profit scientific society with nearly 40,000 members. Fellows of the Academy have been elected by their peers in recognition of their outstanding contributions to the microbial sciences. Through its colloquia program, the Academy draws on the expertise of these fellows to address critical issues in the microbial sciences.

This report is based on the deliberations of experts who gathered for a full day to discuss a series of questions developed by the steering committee regarding the role of complex microbial ecosystems found in built environments. This report has been reviewed by all participants, and every effort has been made to ensure that the information is accurate and complete. The contents reflect the views of the participants and are not intended to reflect official positions of the Academy or ASM.

The Academy acknowledges Karen MacKavanagh for her assistance in editing this report. Additionally the Academy thanks Chelsie Geyer, Ph.D. for her assistance on this project.

Contents of the report may be distributed further so long as the authorship of the Academy is acknowledged and this disclaimer is included.

1. What are built environments and why are these ecosystems important to study?

Built environments are central to our daily lives. Found in areas ranging from rural to urban, they are the structures that humans create to shelter from the outdoors and provide spaces for living, working, playing, and getting places. They are our homes, offices, schools, hospitals, long-term care and specialized nursing facilities, commercial and retail establishments, airplanes, trains, buses, and subway stations, our cars, and even the space station—indoor spaces designed with different forms, functions, and organization to host particular human needs.

Box

Key terms used throughout text.

These spaces are far from inanimate. Humans, pets, pests, and house plants reside in built environments, and all are associated with a range of microbes, tiny organisms that cannot be seen by the unaided human eye. In fact, the number of microbial cells associated with human bodies is greater than the number of human cells that our bodies contain (Turnbaugh et al. 2007). While people may think of microbes as “bad,” most are not. Many microorganisms help keep pathogens at bay and drive critical functions in our bodies, such as digestion.

Figure

Sources of microbial bioaerosols in the built environment may include humans; pets; plants; plumbing systems; heating, ventilation, and air-conditioning systems; mold; resuspension of settled dust; and outdoor air. The green and red dots represent microorganisms (more...)

When humans mingle in the built environment, we share microorganisms with each other and our surrounding space. Microbes are sloughed off with skin cells and dirt; passed through hugs, handshakes, and saliva; and flushed into plumbing systems and carried to septic systems, sewers, and sewage treatment plants. They are on surfaces, in the air, in our tap water, and in the wastewater we create—nearly everywhere. Given such ubiquity and the knowledge that people in the developed world spend more than 90% of their time indoors (Klepeis and Nelson 2001), it is important to understand what types of microorganisms reside in the built environment, how these microbes interact with humans, and how they might impact human health and the economy. Some microbes are pathogenic, particularly to people with compromised immune systems. Others have impacts that we are only just beginning to understand.

With global climate change, we are likely to reexamine how we design and operate the built environment. In doing so, we would be prudent to examine impacts on indoor microbial ecosystems and their effects on human health, comfort, and satisfaction.

2. What microbes are found in built environments?

Trillions of microorganisms contribute to the built environment microbiome, comprising thousands of different species, ranging from single-celled organisms such as bacteria and archaea to microbes with cell structures that are more similar to cells of plants and animals, such as protozoa, fungi, and algae (Adams et al. 2015; Kelly and Gilbert 2013; Konya and Scott 2014; Stephens et al. 2015). In addition, viruses are abundant in these diverse communities of microbes. Since we know little about how they contribute to the built environment microbiome, we do not address them in this report but acknowledge that their importance should be studied.

To identify potential impacts of microbes on people and structures within the built environment, it is important to characterize the biogeography of the microbial community. Which microbes are present? In what numbers? Are the microbes alive or dead, and if alive, how active are they? What kinds of microbial products or metabolites can be found, and what factors drive their concentrations? One of the problems that we face is that the different microbial populations in these communities are quite difficult to quantify given current methods and costs and their variability over time and in space. Nevertheless, this task has been made somewhat easier by developments in molecular biology over the past two to three decades.

The development of DNA sequencing techniques has facilitated the study of microbes in their natural habitat.

Colonization patterns

Despite methodological limitations, we are beginning to understand some of the basic factors that influence the number and type of microbes found in the built environment and confirm some of the conclusions of earlier culture studies. Preliminary studies indicate that indoor spaces have distinct microbial communities. Buildings share many species with the outdoor environment but contain specific taxa that thrive indoors and are more abundant inside than outside (Barberán et al. 2015).

Where do microbes in the indoor microbiome come from? Some come from initial building materials and are brought in by workers during building construction; many others come from building occupants and environmental sources. Humans contribute microbes through loss of skin cells, as well as gut, nasal, oral, and vaginal fluids and semen, while pets contribute through loss of skin, fur, saliva, and feces. Even house plants and fish tanks contribute microbes. The water from centralized drinking water treatment facilities contains microbes that are dispersed when we shower, flush the toilet, and run the dishwasher (Pinto et al. 2012). Outdoor air carries microbes through windows, doors, and ventilation systems, while humans and pets track in microbe-laden soil as well as pollen and dust trapped in clothes and fur. The food that we bring into our homes also contains microbes (Montville and Mathews 2005). And although we don’t like to think about it, insect or rodent pests may introduce additional microbes (Kelly and Gilbert 2013).

Once inside the built environment, microbes are transported through air, water, or the contact of occupants with each other and indoor surfaces. Individual cells or groups of cells may be dispersed multiple times or settle and then thrive, lie dormant, or perish depending on local conditions.

Figure

Coughing and sneezing send microbes onto airborne droplets.

The kinds of bacteria found in the built environment are related to the occupancy and activity patterns of people, plants, and pets in the building and in individual spaces. The greater the traffic, the more exuberant and varied the activity, the greater the microbial biomass and diversity. Moreover, the organization of spaces in the built environment—how they are juxtaposed—shapes the microbiomes present (Kembel et al. 2014). Given the limitless number of ways that we inhabit buildings, it is not surprising that bacteria vary from building to building and room to room (see Table 1) (Adams et al. 2014; Kelly and Gilbert 2013). In fact, the bacterial “signature” of a building is so distinct that it can be used to predict the sex ratio of human occupants or the presence or absence of a cat or dog (Barberán et al. 2015). When an occupant moves to a new house, it may take only a few days for his or her unique bacterial microbiome to reestablish in a new location (Lax et al. 2014).

Table 1.

Signature microbes of various built environments.

In contrast, fungi present in the built environment are strongly influenced by the presence of water and the composition of outdoor fungi (Adams et al. 2013). Common fungi include molds such as Aspergillus, Alternaria, Cladosporium, and Penicillium and wood-degrading fungi such as Stereum, Trametes, Phlebia, and Ganoderma, as well as fungi associated with humans such as Candida, a common yeast associated with skin and mucous membranes. Fungal populations tend to vary primarily by moisture level, climate, and region, with significant regional variation across the United States (Barberán et al. 2015).

Ventilation and airflow play a key role in determining the number and type of microbes present in the built environment. Rooms with natural ventilation through windows and doors have a higher abundance of outdoor fungi and bacteria than those that have sealed windows and mechanical ventilation (Kembel et al. 2012; Meadow et al. 2014). Smaller, older residential structures also tend to have higher relative leakage through walls and around window and door areas than larger, newer structures (Chan et al. 2005). Heating, ventilation, and air conditioning (HVAC) systems filter out some airborne microbes.

Warm temperatures and high moisture tend to promote microbial growth within the built environment (Tang 2009). Microbes thrive in restrooms and kitchens—in sinks, on showerheads and shower curtains, and in and around toilets (Feazel et al. 2009). These areas may become microbial hotspots due to the damp microhabitat and the introduction of specific microbes from food, gastrointestinal and vaginal sources, and the water system (Adams et al. 2014). Leaks and condensation from faulty building construction also may cause moisture accumulation and microbial growth.

Floods lead to extensive microbial growth, carrying “outdoor” microbes and nutrients inside. After Hurricane Katrina, the Centers for Disease Control and Prevention (CDC) estimated that 43% of homes in the New Orleans area were colonized with large, visible colonies of mold (CDC 2006). In Boulder, Colorado, scientists found that air in flooded homes had three times more fungal DNA than did air from nonflooded homes. Moreover, the influence of flooding on the microbiome persisted even after the relative humidity returned to baseline and residents removed flood-damaged material and renovated the damaged rooms (Emerson et al. 2015).

Figure

Mold in a New Orleans building after Hurricane Katrina.

The properties of materials in the built environment also affect microbial growth (Ramos and Stevens 2014). Wood, metal, plaster, and concrete all have different physical and chemical properties of varying appeal to microbes. More-porous materials provide microhabitats for microbes and the opportunity to store moisture. For example, scientists have found that plaster is particularly susceptible to fungal growth after flooding (Anderson et al. 2011). Copper is less prone to colonization and as a result is often the material of choice in hospital design (Mehtar et al. 2008). In fact, laboratory tests show that copper alloys even work as antimicrobials (Michels et al. 2015).

Ventilation and airflow play a key role in determining the number and type of microbes present in the built environment.

Microbial colonization is impacted by cleaning. In the process of cleaning, we remove dust and associated microbes as well as some of the substances on which they live. Chemicals, high temperatures, or UV radiation are used to disinfect surfaces. The more frequently and thoroughly we clean, the less opportunity for microbial buildup on materials and the lower the microbial biomass (Adams et al. 2013; Dunn et al. 2013; Medrano-Félix et al. 2011). Even house walls may be reservoirs for microbial communities, because occupants are less likely to wash walls than floors (Ruiz-Calderon et al. 2016). Hand sanitation is equally important. Proper handwashing and adherence to cleaning protocols minimize the spread of infectious agents in health care settings but may also kill noninfectious microbes (Boyce and Pittet 2002).

3. How does microbial metabolism affect the chemistry of built environments?

Fungi, bacteria, and other heterotrophic microbes break down organic compounds to produce the energy they need for growth and reproduction. When microbes grow on building materials, the result is decomposition and decay. Left unchecked over time, decomposition may undermine the structural integrity of building materials, especially wood, often with catastrophic results. Sadly, we have seen this all too frequently in recent years with the collapse of wood-fortified balconies and decks (Van Derbeken et al. 2015).

Microbes are part of the fine particulate matter in indoor air. Spores and mycelial fragments not only originate from outdoors but are dispersed by fungi and some bacteria (e.g., actinomycetes) growing indoors. Airborne concentrations vary in time and space, reaching 1,000 spores per cubic meter, even in “clean” buildings with no visible mold (Baxter et al. 2005; Nevalainen et al. 2015). Cell fragments, compounds from decomposed materials, and dead microorganisms further contribute to the particle load of indoor air.

Figure

Microbial decomposition in a wood support contributed to the catastrophic collapse of a balcony in Berkeley, CA

Microbes produce a number of additional products that become part of the built environment. Of particular interest and concern are beta-glucans, endotoxins, mycotoxins, and volatile organic compounds (VOCs). In the built environment, these compounds frequently attach to dust particles.

Just as microbes vary in the built environment, so will their metabolic products. VOC, toxin, and glucan production are all influenced by microbe interactions with other organisms as well as the properties of growth substrates. By monitoring the in situ state and developing model systems to study microbial biochemical processes and interactions more closely, scientists can continue to build on our understanding of microbial metabolites in the built environment.

4. How do microbes in the built environment affect human health?

Specific causal links between ill health and indoor microbiomes are difficult to make (Mendell et al. 2011). It is almost impossible to separate the effects of microbes from each other and from those of other stressors such as dust and nonmicrobial volatiles; moreover, we have limited information on human exposure to microbes or microbial by-products (Husman 1996). There are neither uniform diagnostic criteria nor clear-cut biomarkers, and diagnostic categories for health effects are viewed with skepticism by many scientists and physicians. Nevertheless, the apparent association between poor health and mold exposure has led to many postulates that mycotoxins, mold VOCs, and/or other mold metabolites might cause the array of reported symptoms. Despite the lack of consensus about the health risks associated with exposure to molds and their metabolites, experts recommend that fungal proliferation indoors should be prevented or minimized.

Microbes are part of the fine particulate matter in indoor air.

Some of the closest associations between the indoor microbiome and poor health have been documented in moldy buildings that host actinomycetes and fungi, including Penicillium, Aspergillus, and Cladosporium (Pestka et al. 2008). Epidemiological studies have linked these environments to respiratory irritation, allergies, and asthma, as well as secondary respiratory infections caused by bacteria and viruses. Nonspecific symptoms also have been documented, such as headaches and tiredness (Institute of Medicine 2004; Mendell et al. 2011; World Health Organization 2009).

In rare instances, indoor microbiomes have been associated with hypersensitivity pneumonitis. This condition tends to occur in occupational situations such as in greenhouses or mushroom houses, where small biological particles are inhaled and become lodged in the lung. Hypersensitivity pneumonitis is more commonly seen in farming communities, where it is often called farmer’s lung (Husman 1996).

Disease has also been associated with building water systems—areas where Legionella bacteria and other opportunistic plumbing pathogens can thrive (Falkinham et al. 2015). When Legionella bacteria are aerosolized in water droplets and inhaled, they may grow and cause Legionnaires’ disease, a form of pneumonia, or a milder flu-like illness, Pontiac fever. According to the CDC, Legionnaires’ disease results in an estimated 8,000 to 18,000 hospitalizations per year in the United States (http://www.cdc.gov/legionella/fastfacts.html). Recent large outbreaks of disease caused by Legionella highlight the importance of maintaining potable water systems and process water. In the summer of 2015, an outbreak linked to a hotel cooling tower in the Bronx was related to 133 reported cases of Legionnaires’ disease and 16 deaths (http://www.nyc.gov/html/doh/html/diseases/cdlegi.shtml).

Figure

Legionella bacteria may thrive in poorly maintained cooling towers.

Bacteria associated with fecal matter also present health problems indoors. Enterococci, for example, can pass between people, and from colonized surfaces to people, if sanitary measures such as hand-washing and surface cleaning are not performed. Exposure can lead to infection, particularly if the bacteria get into wounds or the bloodstream. Minimizing the spread of enterococci and other microbes is a particular issue at day care centers and elder care facilities, where diaper changing and bedpan use are common (Hodgeson et al. 2000).

Figure

Legionella bacteria in lung tissue

The negative health impacts of opportunistic pathogenic microbes in hospitals are a particular concern and warrant careful consideration during building design and operation. When patients come to the hospital, they may introduce new or additional disease-causing microbes to the building. These may be transmitted through person-to-person contact, person-to-equipment-to-person contact, or sneezing, coughing, vomiting, and diarrhea. Many hospital patients have compromised or underdeveloped immune systems which confer a heightened risk of infection. In 2002, 1.7 million patients in the United States, or 5% of those admitted to hospitals, contracted hospital-acquired infections, contributing to 99,000 deaths (Klevens et al. 2007). A third of these infections were attributed to lapses in proper cleanliness protocols.

Within the hospital, a patient’s treatment has a strong impact on the microbiome and health outcomes. Antimicrobial medications are used to combat infectious disease. Particular care, however, must be taken with antibiotics. Repeated or incomplete use, particularly for the wrong reason (e.g., as therapy for viral infections), may promote antibiotic-resistant populations of microbes. Further, chemotherapy and radiation can make cancer patients more susceptible to infectious disease by damaging bone marrow cells. With fewer bone marrow cells, the patient has a more difficult time producing the white blood cells needed to combat microbial infection.

Patients in proximity to point sources of pathogenic microbes in a hospital are more likely to come in contact with pathogens and become sick. In the absence of proper barriers, hospital construction and renovation can contribute to airborne mold spores and an increase in the number of infections, including fungal pulmonary infections by Zygomycetes and Aspergillus (Kanamori et al. 2015). Further, patients may have an increased risk of acquiring infections from antibioitic-resistant bacteria (e.g., methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, Clostridium difficile, and Acinetobacter) if they occupy a room previously occupied by an infected or colonized patient (Weber and Rutala 2013).

With so many unknowns associated with the transmission of microbes in hospitals and the high stakes at hand, the Alfred P. Sloan Foundation has funded the Hospital Microbiome Project (http://hospitalmicrobiome.com). This project is studying the composition of surface, air, water, and human microbial conditions at a newly constructed University of Chicago hospital before and after the introduction of patients, health care workers, and staff. As the project proceeds, scientists hope to learn where microbes originate, where they thrive, and how they establish themselves, in order to improve patient health outcomes.

Figure

Microbiologist Jack Gilbert Swabs the floor in a new hospital room to collect microbial samples at the new University of Chicago hospital.

5. Is there such a thing as a healthy indoor microbiome?

Of the 1 to 10 million species of microbes on the planet, scientists estimate that only 1% cause disease (Proctor 2014). The remainder contribute to ecosystems in ways that we are only just beginning to understand. In the human gut, for example, there are microbes that are critical for digestion and produce vitamins, antimicrobials, and neurotransmitters (LeBlanc et al. 2013; Lyte 2013). Thus, it is logical to ask if indoor microbial communities can produce conditions that can influence positive health outcomes in occupants.

We currently don’t have an answer. We don’t even have a good definition for a “healthy” indoor micro-biome. However, there are two ways to think about healthy microbiomes—how we can avoid harmful microbiomes and how we can encourage well-being. More is understood on the first of these.

Scientists agree that it is best to avoid unhealthy systems that build up problematic microorganisms associated with disease. This can be done in part through the appropriate design and operation of buildings. For example, architects can design buildings with room partitions or other physical structures that control foot traffic and some airborne microbe transmission. Engineers can ensure that buildings have an optimal air exchange rate and control relative humidity within heating and cooling zones. By keeping the relative humidity lower than 30%, microbial growth can be limited. Windows let in sunlight, which impacts some microbes, as well as outdoor air, increasing air exchange in the building. However, such turnover is beneficial only in areas and at times with good outdoor air quality and needs to be avoided during periods of air pollution.

In addition, we can design and maintain plumbing systems to minimize microbial colonization. Pipe systems should avoid dead zones that allow water to stagnate and develop biofilms that can allow Legionella, Pseudomonas, and mycobacteria to thrive. Water in water heaters can be heated to a high temperature to suppress microbial contamination (Falkinham et al. 2015). Moreover, we can minimize localized moisture problems by detecting and fixing plumbing leaks rapidly, including the pinhole leaks common in older copper pipes. Water meters can be used in residential structures to identify leaks when all water in the building is shut off.

Proper care should be taken to remove reservoirs of dust and mold when they occur. This entails cleaning or replacing dirty HVAC filters, cleaning HVAC ducting, removing and replacing rotten wood from buildings, or getting rid of resident bird populations. By removing drop ceilings, we can eliminate dead spaces that accumulate dust, as well as porous tile material on which microbes are often found (Hodgeson et al. 2000). Such work can minimize the dispersal of pathogenic microbes but will undoubtedly remove many “good” microbes as well.

Figure

HVAC filters can help trap microbes but must be cleaned or replaced frequently.

Hospitals routinely take extra precautions to minimize the spread of disease-causing microbes. Surfaces are cleaned frequently, and rooms include stations to facilitate handwashing. Air streams may be more thoroughly scrubbed for fungal or bacterial propagules, or rooms may be pressurized to keep pathogens out or depressurized to prevent the escape of highly infectious microbes. In some cases, hospitals irradiate the upper portions of rooms with ultraviolet germicidal (UV-C) radiation to kill the microbes above 6.5 feet. As air circulates within the room, part of the microbial load is killed (First et al. 2005).

We also can encourage healthy coexistence with microbes by promoting development and maintenance of effective immune systems and healthy microbiomes. There is still much to learn in this area, but scientists recognize that somewhat paradoxically, exposure to bacteria, viruses, and parasites can help us build immunity that enables us to combat infection. The antimicrobial soaps, antimicrobial wipes, and antimicrobial surfaces that we often use, particularly those containing triclosan, may be doing us more harm than good (Bertelsen et al. 2012; Halden 2014).

Exposure to certain microbes is particularly important in early childhood, when the immune system is still developing. Infants, for example, are less likely to develop asthma and allergies if they live in a house with a dog—and its distinct microbial communities—than in a house without a dog (Ownby et al. 2002; von Mutius and Vercelli 2010). When mice were fed lactobacilli from dogs, their immune system improved (Fujimura et al. 2014). Exposure to farm animals during pregnancy and early childhood also decreases the risk for allergies (Holbreich et al. 2012). Endotoxins in farm dust may work to protect lung epithelial cells (Schuijs et al. 2015).

Figure

Infants who grow up exposed to dog microbes are less likely to develop asthma and allergies.

The type of childbirth also influences the microbial inoculation of children. During vaginal deliveries, babies are colonized by the mother’s vaginal and intestinal microbes. When cesarean deliveries are performed, this inoculation is bypassed and the baby’s first microbial contact is with the room microbiome. For cesarean newborns, this translates to a wholly different complement of microbes, including many skin bacteria and some potential pathogens (e.g., Staphylococcus and Acinetobacter) (Dominguez-Bello et al. 2010). Although scientists are only beginning to explore possible links between immune system development and health outcomes, they have noted an increased incidence of childhood asthma, allergic rhinitis, and obesity in children delivered by cesarean section (Mueller et al. 2015; Renz-Polster et al. 2005).

To increase our understanding of the “healthy” micro-biome in the built environment, we must expand our epidemiologic knowledge. These studies are challenging—investigators need to understand the time, concentration, and route of exposure to microbes and their byproducts, as well as the dose response. It is also important to characterize building factors that may moderate disease so that associations between the built environment and disease can be elucidated (Luongo et al. 2015). As we conduct these studies, it will be important to evaluate risk across socioeconomic groups, age groups, and regions and to bear in mind the energy and carbon costs associated with any change in building design and operation.

6. How do we foster collaborations among scientists who study the built environment using different paradigms?

Assessing indoor microbiomes and identifying links to building design and operation and health outcomes are extremely complex and require expertise from many disciplines. Microbial ecologists, building engineers, architects, public and occupational health experts, and medical doctors all bring specific knowledge, tools, and approaches to the table that can enhance each other’s research.

How do we foster collaboration? At the most basic level, we can provide grants as incentive. Funders can recommend or mandate interdisciplinary collaboration in providing financial support for research projects. We also can provide opportunities for investigators to connect and exchange ideas. By organizing cross-disciplinary sessions or workshops at conferences and/ or providing travel funding for investigators to attend conferences outside of their disciplines, conference organizers can encourage investigators to expand their conversations and explore joint objectives.

Scientists can build Internet platforms to share research findings, protocols, ideas, presentation materials, and data. The microBEnet, a project funded by the Alfred P. Sloan Foundation and run out of the lab of Jonathan Eisen at the University of California, Davis, is a particularly useful resource. Users have access to blogs, simple guides, and social media groups, and they can share slides and videos on the microbiology of the built environment (www.microbe.net). Another useful resource is the mVOC database, which provides an excellent platform to exchange information on VOC emissions from bacteria and fungi. Users can find and share information on VOC structures, signature VOCs of particular microbes, and compound target pathways as well as basic information on microbial VOCs (Lemfack et al. 2014; http://bioinformatics.charite.de/smvoc/).

Communication between investigators also can be improved through the use of standardized and complete metadata. For this purpose, the Genomics Standards Consortium has recently developed an MIxS-BE package defining specific metadata terms associated specifically with studies of the built environment (Glass et al. 2014). Regulatory and investigative bodies such as the U.S. Environmental Protection Agency, the U.S. Food and Drug Administration, the U.S. Department of Agriculture, the Centers for Disease Control and Prevention, and their respective counterparts across the globe should be consulted and encouraged to contribute to discussions on data collection and reduction.

7. Will studying microbiology of built environments change the ways we design, build, operate, occupy, and clean our indoor spaces?

Yes, changes are certainly possible as we strengthen our knowledge of the built environment microbiome, its determinants, and health impacts. The common attitude that all microbes are “bad” needs moderating. The better the public understands known risks and suspected benefits of microbes, the more willing people will be to alter the way in which they clean, occupy, and use buildings. Towards this end, we must ensure that information is transparent and widely communicated using nontechnical language and consistent use of terms.

Changes in building design and construction may be more difficult.

Changes in building design and construction may be more difficult. Widespread adoption of new practices will take policy support and mandated changes in building codes. Experts can facilitate this process by working with policymakers to show how research supports the need for change. Whenever possible, the dialogue should engage existing professional communities and companies with related interests. Obvious allies are the Green Building Council, the American Institute of Architects, the Center for Health Design, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), building scientists/engineers, companies that design hospitals, and those that focus on building sensors and biohazard rooms.

Documented case studies of exemplary buildings and practices and any potential cost savings can facilitate the adoption of sound practices. Forward-looking architects should be enlisted to serve as spokespeople for smart design. Research findings can be used to inform existing standards, such as the WELL Building Standard (http://delos.com/about/well-building-standard/) or the Leadership in Energy and Environmental Design (LEED) standard (http://www.usgbc.org/leed).

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