Breathing easy
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| You'll need these materials. | |
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| Remembering the bottle will be upside down, measure the volume in litres. | |
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| Blow as much air as possible into the bottle. | |
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| What is your lung capacity? |
You will need
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1m of flexible plastic tubing (15mm diameter)
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5L clear plastic bottle/container (Large filtered water bottles are perfect)
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Measuring cup
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Black marker
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Large plastic tub
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Water
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Cup
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Methanol
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Volunteers
What to do
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Find a quiet place outside.
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Slowly fill the plastic container with water one litre at a time, turning the closed bottle upside down and marking a line on the side where the water level sits as you go. This will give you an indication of the water level when the bottle is inverted.
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Continue to fill the container until it is overflowing.
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Half fill the plastic tub with water as well.
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Now for the tricky bit – you might need the help of somebody strong. Quickly tip the container upside-down and into the tub. You’ll lose a bit of water, but that won’t be a big problem.
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Ask a volunteer to hold the container steady and tip it to one side just enough so you can feed the end of the plastic tubing into its neck.
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Make a note of where the water level sits. This will show how much air is in the water container already.
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Take a deep breath, filling your lungs as much as possible, and blow as much air into the bottle as you can. You will force water out of the container, down into the tub.
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Note where the water level sits now, and subtract from it the starting level to find out the volume of air you exhaled.
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Rinse the end of the tube in a mix of one part methanol, three parts water before refilling the container with water and having another person try.
What’s happening?
As you’re sitting quietly, reading Science by Email, it’s unlikely that you'll be taking in deeps breaths. While your breathing is influenced by a range of factors, the average person will inhale and exhale anywhere between 12 and 20 times per minute, and will come nowhere near filling their lungs completely.
Lungs are like massive bunches of balloons you might see a vendor selling at a circus or a fete. Imagine if each balloon was also surrounded by a mesh of thin hoses, and gas could flow across the balloon’s rubber. Those balloons are called alveoli and hold the air we breathe in and out, and the hoses are like the capillaries carrying gases dissolved in our blood. Yet most breathing barely inflates 10 per cent of the balloons.
Calm breathing fills what is called your ‘tidal volume’, which constitutes only a fraction of your total lung space. The deepest breath you can take in is called your ‘inspiratory capacity’; however you’ll never be able to breathe all of the air from your lungs. No matter how hard you push, there will always be a small amount left called the residual volume.
The average adult male has a total lung capacity of about 6L, yet would only be able to blow about 4.5L of water out of the container in this activity.
Applications
Other than your age, there are a number of environmental influences on your lung capacity. Living at sea level means the air is denser, giving your body more oxygen with every breath. If you live higher up, you’ll develop a larger lung capacity to get more out of each inhalation.
Certain chemicals in our environment can also affect the health of our lungs. Cigarette smoke or particle pollution can lead to conditions such as emphysema, which causes the alveoli to break down. Microbes that cause pneumonia make the lungs fill with fluid, making it difficult to breathe.
Asbestos is a naturally occurring material that was once used in large amounts in construction as a form of insulation. If breathed in, its fine, needle-like shape can cause damage to the lungs, creating conditions like the cancer ‘mesothioloma’. Although it’s not used today, demolition and construction workers who deal with old buildings still need to take extra care to avoid sucking in lungfuls of this nasty material.
