What are oxygen levels?

Oxygen levels tell us how much oxygen is around us, just like a cookie jar tells us how many cookies are left.

Imagine you have a big jar full of cookies. Every time you take a cookie, there’s one less in the jar. That’s kind of like what happens with oxygen when we breathe. We use up some oxygen, and that changes the number of oxygen molecules around us, that's the oxygen level.

Think of a breath as taking cookies from the jar. When you’re outside, there are lots of cookies (a lot of oxygen), so your jar feels full. But if you go into a small room with no windows and keep breathing, soon the jar will have fewer cookies, that’s like being in a place with lower oxygen levels.

If the jar gets too empty, meaning oxygen levels get too low, you might feel dizzy or sleepy, just like if you had to eat from an almost-empty cookie jar all day. That’s why astronauts and divers need special equipment, they help keep the jar full of cookies (or oxygen) for longer!