Across
- 2. the activity of treating materials or products using a special industrial process so that they can be used again
- 3. waste material or things that are no longer wanted or needed
- 5. a thick, liquid substance that burns and is used as fuel or as a lubricant
Down
- 1. damage caused to water, air, etc. by harmful substances or waste
- 4. air pollution caused by smoke or chemicals mixing with fog