Imagine striking a match and having everything around you catch on fire, even if you were standing in a wet forest. And while that’s happening, imagine being chased by giant insects.

These are just a few of the things that would happen if you lived in a world where the atmosphere is pure oxygen.
What other things would happen on Earth? Would you be able to survive this?

Oxygen takes up just over 20% of our atmosphere, and the rest is mainly nitrogen. It’s no secret that you need oxygen. It allows us to breathe and is responsible for all forms of life.

If there were no oxygen in the atmosphere, everything would die. Including you! But what would happen if the atmosphere was nothing but oxygen?

At first, it might sound like a good thing. Oxygen is what helps us live and gives our bodies energy. More of it has to be a good thing, right? There are even oxygen bars all around the world that offer hits of 95% oxygen.

These services claim a number of things from making you more productive at work to being able to cure your hangover. If you were able to breathe 100% oxygen all the time, would it make you an extremely energetic, superhuman version of yourself? Nope! Not at all.

Too much oxygen is actually a bad thing. At a certain point, it can be downright poisonous for humans.

If you breathe in too much pure oxygen, too fast, it creates free radicals. Free radicals are unstable atoms that damage cells and they’re linked to a variety of diseases, including cancer and Alzheimers.

They’re also thought to be linked to things like wrinkles and grey hair. So if we were able to survive an extended period of time with pure oxygen in the atmosphere, we’d most likely appear much older.

But that could only happen if we evolved and adapted to live in an oxygen-only atmosphere. If it happened instantly, your chest would be hurting each time you took a deep breath.

Fluid would accumulate in your lungs, and you’d start to become dizzy and light headed. As you kept breathing, your lungs would begin to get damaged, and so would your brain until you lost consciousness and died.

For insects, it might be a different story. Around 300 million years ago, giant insects roamed the Earth. At that time, the Earth’s atmosphere was 35% oxygen, a lot more than the 20% we breathe today. Researchers suspect the increased oxygen was responsible for those giant insects.

It had to do with the tracheal system, a network of tubes that brings oxygen to the insect’s cells and takes away carbon dioxide. If there was more oxygen in the atmosphere, the insects’ tracheas would expand, and their bodies would get bigger.

But what about those crazy fires mentioned before? If you happened to survive long enough to light a match, you wouldn’t last too long after that.

As soon as you brought your flame to something, anything, it would instantly catch fire in a massive explosion. Oxygen is a key ingredient to what makes a fire spread and expand.

If we only had oxygen in our atmosphere, our fires would become massive. What used to be a small campfire, would now be a fiery explosion.

So if you could breathe when there was only oxygen, the giant insects and the Earth burning all around you would make life pretty tough–even impossible. The only way to survive would be to adapt and to make sure fires never happened. And what would your life be like without fire?

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