The Unexpected Science of Farting: ‘Smart Underwear’ and the Human Flatus Atlas

Everybody passes gas. But how often is normal? And when should a bout of flatulence prompt a visit to the doctor? Those questions, once largely unanswerable, are now the focus of a surprisingly detailed scientific inquiry, spurred by a bit of ingenuity – and a willingness to measure farts directly. Researchers are now using “smart underwear” equipped with sensors to track gas production, launching a project called the Human Flatus Atlas to map the surprisingly complex world of intestinal gas.

The journey began with a frustration in the lab of microbiologist Brantley Hall at the University of Maryland in College Park. Hall and his team study the metabolism of gut microbes, but were struggling to accurately measure hydrogen production in a controlled, oxygen-free environment. “We took the sensor out of the chamber, and we were like, ‘Screw it. We’re going to try to measure a fart,’” Hall explained. The results were, to put it mildly, significant. The Hall Lab combines computational biology and microbiology to understand the functions of the human gut microbiome. The initial test, conducted on Hall himself, demonstrated the potential of the technology.

From Lab Curiosity to Wearable Tech

That initial success led to the development of a small, wearable hydrogen sensor – roughly the size of a quarter – designed to be attached to regular underwear. The device, described in a December 2025 publication in Biosensors and Bioelectronics: X, allows for continuous monitoring of hydrogen levels in expelled gas. Here’s significant because hydrogen is a byproduct of the fermentation process carried out by gut bacteria, offering a window into the activity of the microbiome.

Early data from a pilot study involving healthy college-age volunteers revealed a wide range of normal flatulence rates. On average, participants farted 32 times per day, but individual numbers varied considerably, ranging from a low of four to a high of 59 daily emissions. Interestingly, consuming high-fiber gumdrops was associated with increased flatulence in 36 out of 38 participants.

The Human Flatus Atlas: Mapping the Normal Range

Hall’s team is now expanding the study through the Human Flatus Atlas, an ambitious project aiming to establish a comprehensive baseline for normal farting patterns. The goal is to understand how factors like age, diet, and overall health influence gas production. “We grasp what the normal heart rate is, we know what the normal level of cholesterol is, but if you tell your doctor, ‘I’m farting 50 times a day,’ they don’t have really a baseline to compare that to,” Hall notes. Brantley Hall’s research focuses on identifying the bacterial genes underlying health-relevant functions of the gut microbiome.

Volunteers participating in the Atlas project wear the sensors continuously (with a brief pause for showering and recharging) for a period of three to 30 days. They are also asked to photograph their food using a dedicated app, allowing researchers to correlate dietary intake with gas production. Hall reports that most participants quickly forget they are wearing the device, with loss or accidental washing being more common complaints than discomfort.

Three Categories of Tooting: Zen Digesters, Hydrogen Hyperproducers, and Everyone Else

Preliminary findings suggest that people tend to fall into three distinct categories based on their flatulence patterns. “Zen digesters” exhibit minimal gas production even when consuming high-fiber foods, although “hydrogen hyperproducers” are prolific farters. The majority fall into an intermediate group, though the precise characteristics of this “normal” category are still being defined. The most and least prolific participants in the Atlas project will be recognized with 3D-printed plaques.

The project has generated significant public interest, with the initial batch of 800 sensors selling out quickly and over 3,500 people expressing interest in participating. Enrollment is currently paused while the team scales up production, but may reopen to accommodate those on the waiting list.

Beyond Basic Science: A Startup and a Shifting Cultural Conversation

The research has also spurred the creation of Ventoscity, a startup company aimed at helping companies that produce fiber supplements assess the impact of their products on flatulence. This represents a potential commercial application of the technology, demonstrating the broader implications of understanding intestinal gas.

Hall expresses surprise at the level of enthusiasm surrounding the project, noting that despite the social taboo surrounding bodily functions, people are remarkably eager to discuss and measure their farts. “You would consider that this is a kind of a topic people don’t want to talk about, but almost people want to talk too much to me about it,” he says.

What Comes Next: Expanding the Atlas and Refining Our Understanding

The Human Flatus Atlas is an ongoing project, and researchers are actively seeking to recruit a more diverse group of participants to ensure the data accurately reflects the population as a whole. Future research will focus on exploring the relationship between gut microbiome composition, dietary habits, and flatulence patterns. The team also hopes to investigate the impact of factors like age, gender, and underlying health conditions on gas production. The goal is to move beyond simply measuring farts to understanding the underlying biological mechanisms that drive them, potentially leading to new insights into gut health, and disease.