With the rise of cheap gene sequencing, scientists have spent the last decade exploring the previously unknown microbial communities that live in and on the human body. One study last year actually found that people have unique microbial "fingerprints" that can identify us as individuals.
It turns out the same might be true for the microbiomes of different cities.
A group of researchers, publishing in the journal mSystems, reached this conclusion by taking a detailed look at the microbiome of an average office. They wanted to better understand what makes the microbial community of a "built environment" vary—is it the building materials, the occupants, the location inside the office, or perhaps the geography or climate? They sampled nine offices in three very different cities—Flagstaff, San Diego, and Toronto—over the course of a year to find out.
They found that the microbial communities of offices were pretty similar to one another if they were located in the same city. But offices in different cities had more unique signatures—a computer program could predict with 85% accuracy which of the three cities the office was located in, just by knowing its microbial composition.
The people who inhabit an office have some influence, too. Across all nine offices, human skin bacterial communities "were the largest identifiable source" in the samples. About 25% to 30% of office microbes come from human skin. Even grosser? "The human nasal microbiome also appeared to be a small but consistent source of office surface microbial communities." (Memo to staff: Stop picking your nose.)
More generally, the environments we experience indoors do affect our health. Gregory Caporaso, the lead author of the study with Northern Arizona University, told NPR that he hopes it will be possible to eventually design buildings that have healthy microbiomes that can have a positive effect on our health. That would be a good thing, because a typical 40-hour work week results in spending about 25% of our time at the office every year.