Causes of Asthma
		First, there is inflammation (redness and swelling) of the walls of the small breathing tubes. The cells and substances that cause inflammation build up in the wall of the airway. The small blood vessels (also called capillaries) inside the bronchial tubes become leaky. The lining of the airway becomes swollen and produces extra mucus. The inflammation irritates the muscle that surrounds the small breathing tubes. When this muscle tightens, it narrows the airway. This process is called bronchospasm. The inflammation and the bronchospasm combine to make it hard to get air in and out of the lungs.
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