What are blood oxygen levels?

Blood oxygen levels are how much oxygen is inside your blood, like a juice box showing how full it is with juice.

Imagine your blood is like a red delivery truck that carries oxygen from the lungs to every part of your body. When you breathe in, your lungs fill up with oxygen and pass it into the blood. That’s like filling up the truck with juice before it starts its trip.

Sometimes, doctors use a special gadget called a pulse oximeter, it's like a little sticker that goes on your finger. It shines light through your skin to see how much oxygen is in your blood. If there’s lots of oxygen, the light shows one color; if there’s less, it shows another.

Your body needs oxygen to work properly, just like a toy car needs batteries to run. When you're playing hard or running around, your body uses more oxygen, and the "truck" has to make more trips to keep everything going smoothly.