a. Things, like chemicals or waste, get into the air, water, or soil, making it dirty and dangerous for people and nature. b. The process of collecting and changing old paper, glass, plastic, etc. so that it can be used again. c. The place where a particular type of animal or plant is normally found.d. Using an item or material again instead of throwing it away e. Keeping things safe, and the population is all the people living in an area.