environment or optional

3. an even distribution of something.
4. an amount of gas or vapour that smells strongly or is dangerous to inhale.
7. an event causing great and usually sudden damage or suffering.
8. fine, dry powder consisting of tiny particles of earth or waste matter lying on the ground or on surfaces or carried in the air.
11. the action of stopping something from happening.
13. used water, comes from factories and households.
15. the change in the characteristics of a species over several generations.
17. a water-soluble cleansing agent.
19. wave a prolonged period of abnormally hot weather.

1. thick, soft, wet mud.
2. a word thats synonym to demolition.
5. substance added to soil or land to increase its fertility.
6. when the earth shakes.
9. to conceal, protect, or shelter.
10. the envelope of gases surrounding the earth.
11. the presence in the environment of a substance which has harmful or poisonous effects.
12. the gradual destruction or diminution of something.
14. warming a gradual increase in the overall temperature of the earth's atmosphere.
16. life-supporting component of the air.
18. the act of something getting less and less with time (like species).