Across
- 2. co2 is what type of gas
- 7. process of organic wastes with worms
- 8. rethinking before you buy
- 9. type of gas produced in landfills
Down
- 1. a substance that causes undesirable changes
- 3. pollutant that forms just above the earth's surface
- 4. main source of air pollution
- 5. category of waste
- 6. a combination of smoke and fog