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Breathing is the means by which our lungs remove carbon dioxide (CO2) take in oxygen, a gas needed along with glucose to produce energy. The air going in and out of the mouth or nose when animals breathe is called the breath. Without breathing, you will die.
CO2 must be removed because it is a waste product and too much CO2 is poisonous.
The air humans breathe passes into the two lungs, which are protected inside the rib cage. The lungs take oxygen from the air and pass it into our bloodstream. Our blood takes oxygen all around the body.When we breathe out, the lungs get rid of used air. Adults breathe about 18 times a minute, which is more than 25,000 times a day. Children breathe even faster.
People who suffer from asthma, or other breathing incidents that are dangerous, often use an inhaler to help them. The inhaler puffs a drug down into the windpipe. This makes the air passages wider and then can breathe better than they could before. 
- Morris, Neil; Ting Morris (1998). Jim Miles, Lynne French. ed (in English). Children's First Encyclopedia. Branka Surla, Rosie Alexander. II Bardfield Centre, Great Bardfield, Essex CM7 4SL: Miles Kelly Publishing Ltd. .