The PSFS Building in 1985 Quiet reigns! Efficiency is enhanced! The PSFS Building, now known as the Loews Philadelphia Hotel, was the epitome of hermetically sealed indulgence in 1985. (Photo: Jack Boucher, Historical American Building Survey/Wikimedia Commons)

In 1932, the ultimate luxury was to be found in hermetically sealed buildings. In a magazine advertisement for the new Philadelphia Saving Fund Building, the text reads, “Because the windows need never be opened, noise from the city streets is excluded. Distraction is ended. Quiet reigns! Efficiency is enhanced. Concentration is possible.”

Almost 100 years later, most new buildings are still designed with windows that won't ever open — to keep noise out, but more importantly, to create a closed heating and cooling envelope. Such closed systems are more energy-efficient, according to the experts who design them.

But if we've learned anything from the biosphere projects (both world-inside-a-dome experiments failed), it's that it's really, really hard to mimic the free cleaning and detox services the natural world provides for air, water and soil. No human system has yet matched it on a long-term basis. At the same time, while there's lots of speculation about indoor air quality issues in closed-ventilation buildings, we don't actually know exactly what all the problems might be — or how they impact human health.

We have a lot to learn about the indoor microbiome

Scientists are looking at the microbiomes created inside buildings for answers. The foundational health of our indoor air (as in our bodies) starts with microbes, and that's why a new research project to better understand indoor air is starting with that premise. The National Academy of Sciences (NAS) is currently "...examining the formation and function of microbial communities in built environments, the impacts of such microbial communities on human health, and how human occupants shape complex indoor microbiomes," according to details on the NAS site.

"We know quite a bit more about how the human microbiome — despite the fact that it's a new field — than we do about the indoor microbiome," says Joan Bennett, committee chair of the study, in the video above, in which she details why this work is so important. (Skip to 3:00 for specifics on the microbiome.) She says this research is in its infancy, so part of the study's aim is to figure out where to focus attention in the future.

Most of spend about 90 percent of our time indoors

buildings in a typical big city downtown Many city buildings were created to keep the elements out, which is good for the heating bills, but not necessarily good for the people inside. (Photo: Imaake/Shutterstock)

Only about 20 percent of the microbes in a building come from the humans in it, Yale University professor and chemical engineer Jordan Peccia told Wired. Peccia studies how microbes move and is part of the NAS study. “When you come into your home, or your office, you’re completely and continually bathed in those microbes.”

Since most people spend about 90 percent of their time inside, this study and those that follow could have significant impacts on understanding human health issues and diseases. The study's participants, including engineers and architects, want to learn what building materials and types of architecture best support a healthy microbiome.

We do know that indoor air quality in our homes is much lower than outdoor air — even in cities. The quality of your home's air depends on many factors, including if anyone smokes cigarettes inside; what kind of paint you used and what you clean with (both can off-gas volatile organic compounds, or VOCs); what kind of heating system you have; how many air-cleaning plants you have; and how often you flush your home with fresh air.

But we have no real understanding about how microbiomes might counteract — or exacerbate — those more obvious toxins. But we'll have a better picture soon, which will potentially make going to work or school a lot better for you.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.