Given a scientific question, generate a correct answer to it.

Q: Muscle atrophy due to age is called what?

A: sarcopenia
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Q: What is the term for a substance that increases the rate of a chemical reaction but is not changed or used up in the reaction?

A: a catalyst
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Q: What common air pollutant is characterized by its sharp odor and often triggers asthma attacks?

A:
nitrogen dioxide
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