2. Red: represents harmful substances, and is sometimes marked with orange. Harmful substances include waste batteries, fluorescent tubes, paints, expired drugs, cosmetics and other substances that are not recyclable and have certain pollution hazards.

3. Green: In the case of a variety of plastic trash cans, green represents kitchen waste, which can be used as fertilizer for plant nutrients, and can be decomposed and absorbed by natural microorganisms and plants after burial, thus playing a role in recycling waste.

4. Blue: It means recyclable garbage, including valuable substances such as plastic, paper and metal, which will be included in the waste recycling system for resource recovery.

5. Gray: garbage other than harmful substances and recyclable substances, bricks, ceramics, muck and other wastes that are difficult to recycle are generally burned and buried.