Raven sets two printed pages on the Windowsill. "Two tables, same topic," she says. "Breaths per minute."
Rocket reads the first. "Adult at rest, 12 to 20." He reads the second. "Average healthy adult at rest, 12 to 18."
"What do you notice?" Raven asks.
"They almost match, but not quite," Rocket says. "Different pages, different numbers."
Nova hovers over the pages. "Both come from the same library," she says. "Why might two pages differ?"
"Different groups of people counted," Rocket guesses. "Different days."
Raven nods and points at a third line. "Infants, 30 to 60. Babies breathe fast." Rocket whistles.
The National Library of Medicine runs the MedlinePlus medical encyclopedia. Two of its pages give breathing rates.
One page says a normal breathing rate for an adult at rest is 12 to 20 breaths per minute. For an infant, 30 to 60.
Another page, on vital signs, gives the resting range for an average healthy adult as 12 to 18 breaths per minute.
The same vital signs page lists the resting pulse for an average healthy adult as 60 to 100 beats per minute.
| Group | Breaths per minute at rest | Source page |
|---|---|---|
| Adult | 12 to 20 | Breathing rate page |
| Average healthy adult | 12 to 18 | Vital signs page |
| Infant | 30 to 60 | Breathing rate page |
The OpenStax textbook Concepts of Biology adds an average. Humans not exerting themselves breathe approximately 15 times per minute.
The text works that out further: about 900 breaths an hour, or 21,600 breaths per day.
A second OpenStax text, Biology 2e, gives 12 to 15 breaths per minute under non-exertion conditions.
It also says both the breathing rate and the size of each breath are closely regulated when oxygen demand increases.
| Measure | Value | Source |
|---|---|---|
| Average resting breaths per minute | about 15 | Concepts of Biology |
| Breaths per hour | about 900 | Concepts of Biology |
| Breaths per day | about 21,600 | Concepts of Biology |
| Resting range | 12 to 15 | Biology 2e |
The two adult ranges, 12 to 20 and 12 to 18, nearly agree. Different pages were written for different purposes.
Scientists expect small differences like this. Two pages written at different times can set the edges of a range slightly differently.
Your Wednesday numbers are from one person on one day. They may land inside or outside any range, and that is fine.
| Statement | True or false? |
|---|---|
| Both adult ranges start at 12 breaths per minute. | ? |
| Infants breathe more slowly than adults at rest. | ? |
| A range gives room for many different people. | ? |
| Your own count must match the table exactly. | ? |
Excellent data work. Tomorrow you will explain why breaths and beats rise together, and review the week.