Ever wonder how much air your car breathes?
Most people are aware of carbon dioxide emissions and how CO2 is a greenhouse gas that causes global warming and climate change. But have you ever wondered about the other half of this equation? What about all the oxygen that is being burned to make carbon dioxide? Could the problem really be too little oxygen, NOT too much carbon dioxide?
Ever wonder how much air your car breathes?
Most people are aware of carbon dioxide emissions and how CO2 is a greenhouse gas that causes global warming and climate change. But have you ever wondered about the other half of this equation? What about all the oxygen that is being burned to make carbon dioxide? Could the problem really be too little oxygen, NOT too much carbon dioxide?

How much oxygen does a car breathe?

Oxygen consumption compared to carbon dioxide emissions.

We are all aware of our reliance on fossil fuels and their byproduct of greenhouse gases and poisons. But have you ever wondered about the oxygen needed to burn the fuel? As mankind burns more and more fuel, we are also burning more and more oxygen.

How much oxygen does a car burn?

How much oxygen does a car burn infographic. An illustration showing that the volume of oxygen burned per gallon of gas is bigger than a car.
As this infographic says, in ideal circumstances, a car burns 2038 times more oxygen than gasoline as measured by volume or about 3.8 times more oxygen by weight.

That’s ideal, but engines are very inefficient. Poor combustion can lead to an increased consumption of fuel and oxygen. Poor combustion also leads to pollutants being created like carbon monoxide, and nitrogen oxides and sulfur dioxide, which cause acid rain. Often, the raw gas is vented unburned out the tailpipe. But even raw gas will react with the oxygen in the atmosphere.

The average U.S. citizen consumes more than 2 tons of oxygen per month. That is about 1.8 times more oxygen being consumed than carbon dioxide is being produced.


Living a worse-case scenario

This graph assumes perfect conditions; however, the combustion engine is probably the most inefficient invention ever made. The explanation is fascinating:

In a perfect world the balanced equation for combustion looks like this:

2 C8H18 + 25 O2 => 18 H2O + 16 CO2 + Δ

Which means: Octane + Oxygen => Water + Carbon Dioxide + Energy
Or, 2 molecules of octane (pure gasoline) burned with 25 molecules of breathable oxygen (molecular oxygen) equals the byproducts of 18 molecules of water and 16 molecules of carbon dioxide.

Gas (C) + Oxygen (O2) = Carbon dioxide (CO2) or Carbon monoxide (CO).

In other words, we can see that a car burns much more oxygen than it produces carbon dioxide; meaning, we are depleting the oxygen from the atmosphere at a much greater rate than we are contributing global warming gases. Lifeforms can use the water and carbon dioxide to grow; however, the oxygen is locked away from a breathable form. The only feasible way to release the oxygen is through the complex and time-consuming process of photosynthesis; as you can see from the chart above it took the Earth about 2.5 billion years to fill the atmosphere with enough oxygen to sustain life.

But that is not the worst part of our story: much of the oxygen is bonded with pollutants, which permanently removes the oxygen from a form that plants or animals can recover. For example, most vehicles use fuel with a 87% octane rating. The other 13% are additives, such as: ethanol, heptane, lead and other impurities. This 13% bonds with the oxygen to create pollution like soot, carbon monoxide, sulfur and nitrogen dioxides (acid rain), and many more toxins and carcinogens. Additionally, the average vehicle emits about 3% unspent raw fuel in the exhaust, which also directly reacts with the oxygen to form pollution.

Adding insult to injury, the combustion engine only uses about 18%-20% of the energy to move forward. Most of the energy is lost to heat or the friction of breaking. Furthermore, most engines are worn out, and most drivers accelerate and decelerate at rates that burn extra fuel.

The bottom line: All these inefficiencies and byproducts have the detrimental side-effect of not only poisoning the Earth and her production of oxygen, but also eroding the ecosystem’s ability to repair itself. This unforeseen and unintended consequence forces humans to consume even more materials to fix the problems the pollution creates, which creates more pollution in the downward spiral of life.


* Measured by volume. If by measured by weight, a car burns about 4 times more oxygen than gasoline (octane); and, if measured by molecules a car uses 12.5 times more oxygen molecules than octane molecules.

** Sources: Science!

How much oxygen does a person breathe compared to a car?

As pictured above a car consumes as much oxygen in one hour as the average person breathes in 6.2 days.* This assumes that the car burns 2 gallons per hour with a perfectly efficient engine (above we saw combustion engines are far from perfect) averaging about 24.9 MPG. This is the new record-breaking national fuel economy, which is for a brand new car, with good fuel, traveling at average speeds without frequent stops. **We are also assuming the person has an active fitness level.

How much oxygen does a person breathe? Infographic. This illustrates that the huge volume of oxygen used by a car in one hour takes a person 6.2 days to use.
In one hour, a car burns approximately 2 gallons of gas to travel about 55-70 miles. It would take the average person 6.2 days to breathe the same amount of oxygen to stay alive with minimum activity.

The oxygen in our atmosphere is being measurably and quickly reduced. Oxygen depletion, in our opinion, will soon be recognized as the greatest crisis humanity has ever faced. And it will probably happen in our lifetime. It is critical to start changing our habits and infrastructure while we still can. Because as we all know, we can’t simply stop driving our cars tomorrow. Which, by the way, is another great reason to ride a bike. Especially since one minute of driving your car consumes the equivalent oxygen that 5 people breathe in one day — that’s a lot of bicycling.

The oxygen content of the earth's atmosphere infographic.
This graph shows that the oxygen content in the Earth’s atmosphere is not constant. In fact, for two billion years there was no oxygen at all. Then the oxygen levels went all the way up to about 39% in the Permian Era then suddenly dropped. Currently, it is assumed to be 20.946% at sea level. It’s hard to measure and there isn’t much data, but the numbers have been dropping.
Global oxygen depletion logo. An illustration of the Earth as a big O2 molecule.

Join our Global Oxygen Depletion Facebook Page and follow some current thinking, and maybe lend some of your own.

Stay tuned for Scott’s upcoming book about oxygen depletion. Join our mailing list to get news. Update 2021: I’m still working on this. It’s been a tough project, but I plan to publish soon one way or another.

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