The graph below shows three areas. People with normal airways are in area A. People with asthma always have airways that over-react. They are in area B. Being near a cat causes the airways to be more sensitive. As a result, symptoms appear. This occurs in area C. In this example, symptoms are gone within ten days. But the airways are still over-sensitive. This makes a person more likely to react to other triggers. If a person then gets a head cold, asthma symptoms will show up again and will last even longer.

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