Can humans breathe the air on Mars?

Suppose you were an astronaut who just landed on the planet Mars. What would you need to survive?

For starters, here’s a quick list: water, food, shelter — and oxygen.

Oxygen is in the air we breathe here on Earth. Plants and some types of bacteria provide it for us.

But oxygen isn’t the only gas in Earth’s atmosphere. It’s not even the most common. In fact, only 21% of our air is made up of oxygen. Almost everything else is nitrogen – about 78%.

Now you may be wondering: if there is more nitrogen in the air, why do we breathe oxygen?

Here’s how it works: Technically, when you breathe in, you take in everything that’s in the atmosphere. But your body only uses the oxygen; you lose the rest when you exhale.