Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.
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Question: Question: What are the two main types of air pollutants? Answer: primary and secondary

Answer: There are two main types of air pollutants: primary and secondary. Most air pollutants come from burning fossil fuels. Some come from burning forests. Some are due to the evaporation of chemicals.

Question: Question: Located above the stratosphere, what layer is the place where meteors burn up? Answer: mesosphere

Answer: The mesosphere is the layer above the stratosphere. Temperature decreases with altitude in this layer. Meteors burn up here.

Question: Question: What forms when nitrogen and oxygen combine at high temperatures? Answer: nitrogen oxide

Answer:
Nitrogen oxides form when nitrogen and oxygen combine at high temperatures. This occurs in hot exhausts from vehicles, factories, and power plants.