======Lung Capacity Test======


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**Alternative titles:** Bottle and Tubing Lung Capacity
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====Summary====                   
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====Procedure====  
  - Gather a large clear plastic bottle, a container or sink of water, a measuring jug, a waterproof marker, and a length of rubber or plastic tubing.
  - Use the jug to add 200 ml of water at a time to the empty bottle, marking a line at each 200 ml increment until you reach the top.
  - Fill the bottle completely with water, cap it, and submerge it upside down in a water-filled container so no air enters; remove the cap while the opening stays underwater.
  - Feed one end of the tubing up into the mouth of the inverted bottle while keeping the bottle opening underwater to prevent air leaks.
  - Take a deep breath, seal your lips around the free end of the tube, and exhale steadily into the bottle to push water out and trap your breath as an air space.
  - Count how many marked 200 ml intervals the water level drops; multiply the count by 200 ml to estimate your vital capacity.
  - Repeat 2–3 times with rest between trials and record the best consistent value.



====Links==== 
Lung Capacity - a BodyWorks On Tour science experiment - Glasgow Science Centre: 
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📄 How to measure your lung capacity - BBC Bitesize: [https://www.bbc.co.uk/bitesize/articles/zm3xh39#zxyhhcw]]\\


====Variations====
  * Use different increment sizes (eg 100 ml marks) for finer resolution in smaller lungs.
  * Compare resting measurements with values after light exercise (ensure adequate rest before repeating).
  * Normalize results by height or age and plot class data to look for trends.
  * If available, compare bottle results with a handheld spirometer to check accuracy.



====Safety Precautions====
  * Use individual, clean mouthpieces or disinfect the tubing between users to prevent cross-contamination.
  * Do not perform the test if you have a respiratory infection or uncontrolled asthma; stop if you feel dizzy or short of breath.
  * Avoid hyperventilating before the exhalation; breathe normally, then take one deep breath to start.
  * Keep the bottle opening underwater during setup to prevent sudden water spills and to maintain a seal.
  * Supervise handling of containers filled with water to prevent slips or spills; wipe up any water immediately.




====Questions to Consider====
  * What is vital lung capacity? (The maximum volume of air you can exhale after a maximal inhalation.)
  * Why do we multiply the number of lines by 200 ml? (Each line represents a calibrated 200 ml volume, so the count times 200 ml equals displaced air volume.)
  * Why must the bottle be inverted and underwater? (To trap exhaled air in the bottle and force an equal volume of water out, enabling displacement measurement.)
  * Which factors affect lung capacity? (Age, height, sex, and fitness level; training can increase capacity to a degree.)
  * What happens in the chest when we exhale? (Intercostal muscles and diaphragm relax, chest volume decreases, pressure increases, and air is pushed out.)
  * How could you improve measurement accuracy? (Use smaller increments, ensure a tight seal around the tube, read levels at eye height, and average multiple consistent trials.)