The environment

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Across
  1. 6. The condition of being populated with excessively large numbers.
  2. 7. A chemical used for killing insects.
  3. 8. Fuels such as oil, coal and natural gas.
  4. 10. A colourless, odourless gas produced by burning carbon and organic compounds and by respiration. It is naturally present in air (about 0.03 per cent) and is absorbed by plants in photosynthesis; the most abundante of the greenhouse gases.
  5. 11. Fog or haze intensified by smoke or other atmospheric pollutants.
  6. 12. The natural home or environment of an animal, plant, or other organism.
Down
  1. 1. A colourless, odourless gas produced by burning carbon and organic compounds and by respiration. It is naturally present in air (about 0.03 per cent) and is absorbed by plants in photosynthesis; the most abundante of the greenhouse gases.
  2. 2. Gases that trap the heat of the sun in the earth's atmosphere, producing the greenhouse effect.
  3. 3. Reduction in the concentration of ozone in the ozone layer.
  4. 4. Contamination of the air, water, or soil with substances that can cause harm to human health or the environment.
  5. 5. Someone who catches and kills animals illegally.
  6. 9. A prolonged period of abnormally low rainfall, leading to a shortage of water.