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1
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the second layer of the atmosphere
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2
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atmospheric layer closest to Earth
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3
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one of the major air pollutants
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4
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the mixture of sulfur dioxide, sulfuric acid, and suspended solid particles
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5
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chemicals emitted directly
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6
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when exhaust reacts to sunlight
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8
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the presence of chemicals in the atmosphere
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11
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the falling of sulfuric and nitric acids
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12
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causes lung disease and suppresses plant growth
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1
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chemicals formed with primary pollutants mix with natural gases
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7
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filters out harmful UV light
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9
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thin layer of gases surrounding the Earth
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10
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colorless, odorless radioactive gas that seeps into basements
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