Here's a neat way to measure how much air your lungs can
hold.
What you need:
- Water
- 2 litre plastic bottle
- Deep bowl - washing up bowls are ideal, but make sure
it's clean!
- Masking tape
- Measuring jug
- Beaker
- Flexible plastic tubing
- Marker pen or biro
How to:
- Attach a strip of masking tape to the plastic bottle, from
bottom to top.
- Fill the measuring jug with 50ml of water and pour the water
into the bottle. Mark the water level on the tape.
- Repeat until you've marked right up to the top of the bottle -
the bottle should be full.
- Fill the washing up bowl with around 10cm deep of water.
- Completely cover the mouth of the bottle with your hand, so no
water can escape.
- Invert the plastic bottle into the bowl of water.
- Don't remove your hand until ALL of the mouth of the bottle is
completely underwater.
- Insert one end of the plastic tubing into the water bottle.
Hold onto the other end.
- Take a deep breath in. Exhale into the plastic tubing.
- Measure how much air is now in the bottle. Count up the number
of lines where there is air, not water. Multiply the number of
lines by 50 ml.
For example: 10 lines x 50 ml = 500 ml of air. Your lung
capacity - how much air your lungs can hold - is 500 ml.
What's happening?
You've just made a spirometer - a device that doctors use to
measure lung capacity. Blowing air from your lungs into the bottle
displaces some of the water. You replaced the volume of water with
the same volume of air from your lungs. This is your lung
capacity
Try it on friends or your parents. Do taller people have a
bigger lung capacity? Why does size make a difference?