Across
- 2. Human needs _________________________ in our body. This gas is needed to release energy.
- 5. _________________________ dioxide is not an air pollutant, but it can lead to global warming.
- 7. During lightning, nitrogen and oxygen combine to form nitrogen _________________________.
- 8. sulfur dioxide is produced during the burning of _________________________ fuels.
- 11. This gas called sulfur _________________________ is produced during volcanic eruptions.
- 12. When the PSI is between 101 to 150, it is in the _________________________ range.
- 13. The temperature in engines are high, which can produce _________________________ oxide.
- 14. Plants take in carbon dioxide to make food. This process is called _________________________.
- 15. Sulfur dioxide can also be produced when _________________________ erupts.
Down
- 1. When the PSI is between 51 to 100, it is in the _________________________ range.
- 3. Dust and soot are examples of _________________________ matters.
- 4. Carbon _________________________ is produced due to incomplete burning of fossil fuel.
- 6. There are four main _________________________ in air. They are harmful to us.
- 9. Particulate matters can be produced during _________________________ fires too.
- 10. Air can be polluted by man, or by _________________________ phenomena such as volcanic eruptions and lightning.