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How Scientists Count Farts, High school

Dried beans in many colors at a farmers market

A fart is gas that leaves your body through your bottom. For many years, doctors said healthy people fart about 10 to 14 times a day.

Do you think healthy people fart more than 14 times a day?

I’m farting for science!

Dr. Raven joins a fart study at the University of Maryland. She wears a sensor on her underwear for three days, and the sensor counts her farts by the hydrogen gas in them. Old counts said people fart 10 to 14 times a day, and the sensor study found far more.

A colorized electron microscope image of a cluster of oblong E. coli bacteria, magnified 10,000 times
Inflation, a steady rise in prices, comes from Latin inflāre, “to blow on or into, puff out,” with the same flā- root.

Your word of the day is

FLAY-tus

fla-to blowfrom Latin flāre
-tusthe act offrom Latin -tus

Gas made in the intestines and passed out of the body. Flatus is the science word for the gas in a fart.

A woman asleep in bed under blankets in morning light

People kept their own counts in the 1979 and 1996 studies, and a hydrogen sensor found an average of 32 a day.

Which two reasons could make counts that people keep for themselves come out lower than counts from a sensor?

A labeled diagram of the human digestive system, from the mouth through the stomach and intestines

In a 1991 study, 10 healthy volunteers wore a flexible tube, placed in the rectum, that collected their gas for 24 hours. When 6 of the volunteers drank a liquid diet with no fiber for 48 hours, the hydrogen in their gas nearly disappeared.

What does the drop in hydrogen on a no-fiber diet tell you about where the hydrogen in flatus comes from?

Crowds of people walking across a street crossing in Tokyo

In the same 1991 study, the volunteers also wrote down each time they noticed passing gas, a median of 8 times. The number of times a volunteer noticed passing gas did not line up with how much gas the tube collected.

What does the 1991 tube study suggest about using people’s own notes to measure gas?

Two scientists working side by side at computers in a laboratory

The Smart Underwear detects farts by the hydrogen gas in them. In the video, Raven asks, “What counts as a fart?”

Picture a careful counter wearing a sensor that works correctly. How could the person’s count and the Smart Underwear’s count still disagree?

A scientist at the National Cancer Institute studies DNA data on a computer

Claim, evidence, reasoning

Older studies, many based on counts people kept themselves, found about 10 to 14 farts a day. The Smart Underwear study found an average of 32.

Which claim about how often healthy adults fart has the best support?

A bedside lamp glowing beside a rumpled white bed at night

Claim, evidence, reasoning

Which evidence backs the claim that about 32 farts a day is closer to the truth?

Tweezers placing a small black microchip onto a green circuit board

Claim, evidence, reasoning

Which reasoning connects the evidence about sleep and memory to the claim that 32 farts a day is closer?

Close-up video of kidney beans falling into a white bowl

Zen Digesters eat 25 to 38 grams of fiber a day yet pass little gas.

How could a Zen Digester eat 25 to 38 grams of fiber a day and still make little gas?

Video of a scientist using a pipette inside a lab safety cabinet

Which measurement would test whether a Zen Digester’s gut microbes explain the low gas?

A hand-drawn line graph on paper with a metal ruler and two pens

Older studies, many based on counts people kept themselves, put the normal number at about 10 to 14 farts a day. A hydrogen sensor now puts the average at 32.

How does the Smart Underwear study show that a number in science can change when scientists find a better way to measure?

A digital clock glowing in a dark room late at night

Lesson complete

Today’s word

flatus

FLAY-tus

Gas made in the digestive tract and passed out through the anus.

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Sources
  1. Santiago Botasini, Brantley Hall and colleagues, University of Maryland, Biosensors and Bioelectronics: X, 2025
  2. Brantley Hall’s lab, University of Maryland, ClinicalTrials.gov, NCT07134543
  3. Michael Levitt, Digestive Diseases and Sciences, 1979
  4. J. K. Furne and Michael Levitt, Digestive Diseases and Sciences, 1996
  5. J. Tomlin, C. Lowis and N. W. Read, Royal Hallamshire Hospital, Sheffield, UK, Gut, 1991
  6. Emily Brindal and Danielle Baird, CSIRO, Australia, JAMA Network Open, 2026
  7. I. Rowland, G. Gibson, A. Heinken, K. Scott, J. Swann, I. Thiele and K. Tuohy, European Journal of Nutrition, 2018
  8. N. W. Smith, P. R. Shorten, E. H. Altermann, N. C. Roy and W. C. McNabb, Gut Microbes, 2019
  9. University of Maryland, “UMD Scientists Create ‘Smart Underwear’ to Measure Human Flatulence”, February 11, 2026
  10. Human Flatus Atlas, the study’s enrollment site
  11. Vision and Change core concepts and competencies, as summarized in Brownell and others, CBE Life Sciences Education, 2014
  12. Word origins from Dictionary.com: flatus, inflate, inflation, conflate, flatulent, microbiome, micro-, bio-, biome, -ome, microbe
  13. Spanish and Italian words from Wiktionary: inflar, fiato
  14. Video quotes from YouTube’s auto-generated captions