environment

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Across
  1. 2. of pollution affecting rivers and lakes (5)
  2. 3. thin layer of gases around Earth (10)
  3. 6. down trees (11)
Down
  1. 1. from the sun (6)
  2. 2. gradual increase in Earth's temperature (7,7)
  3. 4. substance in the air, water, or soil (9)
  4. 5. endangered polar region (6)
  5. 7. use again instead of throwing away (7)
  6. 8. essential for human survival (6)