Every breath you take

With “every breath you take” you inhale and exhale air. But how much air is there in one breath? And how much do we breathe in a lifetime?

To calculate all the breaths you take in a lifetime we have to know a couple of things. First of all we have to know the size (volume) of an average breath. Secondly we have to know how frequent we breathe (number of breaths per minute). And finally we have to decide how long you are going to live. Let’s see if we can find some answers.

The volume of a breath

The volume of one breath can vary a lot, but we are looking for an average to work with, which is the so called “tidal volume”. Tidal volume is the lung volume representing the normal volume of air displaced between normal inspiration and expiration, without applying extra effort. A typical value would be about 500 ml (according to Wikipedia), which is half a liter. If you want to know tidal volumes for yourself you can use an estimate of 7 ml/kg bodyweight.

Breathing cold air

The breathing frequency

The average breathing frequency (or respiratory rate) in a healthy adult at rest is 12-18 breaths per minute (according to Wikipedia). This is of course a very rough estimate. Individuals that are not healthy, not at rest, or not adult, have different rates. So let’s just pick a number for our calculation. We will work with 15 breaths per minute. That’s 900 breaths per hour, 21,600 breaths per day, or 7,889,400 breaths per year. Almost 8 million breaths per year for a healhy adult at rest.

One lifetime

If you have “no time to breathe” your lifetime could soon be over. But what’s an average lifetime? According to Wikipedia, the current world average for life expectancy at birth is 67.2 years. It varies from country to country, but it’s a number to work with, so let’s use 67.2 years as our “life time” number.

How many liters of air do we breathe in a lifetime?

With the above figures of 0.5 liters/breath, 15 breath per minute, and 67.2 years in a lifetime we can calculate our total breathing volume:

There are 60 x 24 X 365.25 minutes in a year. This is 525,960 minutes.

In a lifetime (of 67.2 years) we have 35,344,512 minutes (so you have about 35 million minutes of breathing space).

An average person will breathe 0.5 (liters/breath) x 15 (breaths/minute) x 35,344,512 (minutes/lifetime), which equals 265,083,840 liters/lifetime. More or less 265 million liters of air.

So how much do we really breathe?

We have calculated that we breathe about 265 million liters of air in a life time. Is that much or not? Let’s try to visualize it.

Our 265 million liters of air fit in a cube with sides of about 64.2 meters long.

It also fits is a sphere with a radius of 39.85 meters. So if we spend our lifetime filling up a balloon, it will have a diameter of almost 80 meter by the time we breathe our last breath.

St. Peter’s Basilica in Vatican City has a gross volume of 1.2 million cubic meters. Enough for the lifetimes of about 4.5 persons.

More considerations

Weight of air

Perhaps a volume of air of 64 x 64 x 64 meters doesn’t look so impressive. What about the weight of all this air? Actually, air is much heavier than you would expect. The density of air at sea level is about 1.2 kg/m3. Our lifetime of breathing (about 265,083 m3) thus involves about 318,100 kg of air. So if you weigh 70 kg you breathe over 4,500 times your own weight in your lifetime. You breathe about 13 kg of air per day, which is more than you eat.

A lot of people breathe a lot of air

So we have seen that an average person needs about 318,100 kg of air. The world has currently about 7 billion people. Together they will breathe 318,100 x 7,000,000,000 kg of air in their life time. That’s a big figure, so let’s write it in scientific notation. It’s 2.23 x 1015 kg of air.

How much air is there on earth?

Wikipedia mentions that according to the American National Center for Atmospheric Research, “The total mean mass of the atmosphere is 5.148 x 1018 kg. That’s more than we need. For every kg of air we breathe, there are 2,300 kg available in the atmosphere (some of it quite high up though). That seems a lot, but we forgot that we didn’t consider yet that elephants, ducks and sloths also breathe. Anyway, I need a breath, so I will calculate that another time.

By the way

Every breath you take is a song by The Police.