Mind & Body

Your Exposome Is the Friendly Cloud of Germs That Surrounds You

You've probably heard of the microbiome, the collection of microscopic organisms that make their homes deep within your body. You probably also know (at least if you read Curiosity) that those tiny hitchhikers are just as much your friends as your foes. Here's some even better news. Not all of your invisible sidekicks are on the inside. Your exposome is the cloud of microbes that surrounds you everywhere you go — and we just developed a whole new way to explore it.

Related: How Long Should You Wash Your Hands?

Living on Cloud Mine

It might not feel especially comforting to hear that there's a cloud of "millions, billions, trillions of bacteria, yeast, cells, and cell parts" surrounding you at all times (as Nick Stockton of Wired put it), but these little critters are mostly benign. This cloud is called the exposome, and any time you exhale, scratch a dry patch of skin, and yes, fart, you're adding to that invisible community. The actual composition of the cloud will depend on a lot of different factors: your diet, your genes, your pets, and your hometown, among others. In 2015, a group of researchers from the University of Oregon published a groundbreaking study showing that indeed, exposomes can differ enormously from one person to the next.

Led by James Meadows, the study tasked three participants to sit alone in a sanitized chamber filled with filtered air. Each was dressed in an identical, brand-new set of clothing, seated in a disinfected computer chair, and were given a sterilized laptop with which to communicate with the researchers. There they stayed for four hours, after which they took a short break and returned for another two hours. Afterward, the air was filtered again and the organic material was collected. Because of their careful precautions, all of that organic material was guaranteed to have originated from the person, either by being expelled directly from their body or by hanging on from their brief foray into the outside world.

The team wasn't surprised to find that they could tell if a human being had been in the room based on the amount and type of microbes in the air. But they were surprised to find out just how unique each person's exposome was. When they later performed a similar, 90-minute experiment with eight more volunteers, they found that all 11 exposomes differed widely enough that each individual could be identified based on that data alone. It sounds like it could be a thrilling new tool in a detective's inventory — imagine being able to grab the exposome profile of a suspect right from the air. The problem, of course, is that it would only work on "Law and Order: Sterilized Chamber Unit." But there are plenty of other applications for an analysis like this, and to that end, a new study has been able to paint an even more accurate portrait of the exposome than ever before.

Downloading the Cloud

Maybe a database of the exposomes of the world's most notorious serial killers won't happen anytime soon. But there's still a whole lot you can learn by identifying your little buddies. Thanks to an ingenious repurposing of an air-monitoring device, researchers at Stanford have been able to build precise profiles of various people's microbial clouds. Because these air monitors clip right on to participants (no filtered air here), the researchers were able to track environmental influences, seasonal changes, and any other particulate spikes. Because of the portability of the devices, this method could be used to gauge the health of a person's exposome outside of a laboratory setting. In other words, you could track your allergy flare-ups to specific changes in your exposome — no more blaming flower pollen for what the trees have done.

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Written by Reuben Westmaas October 12, 2018

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