Now most plastic cans that can be discarded after use are affixed with a number (from 1 to 9) that indicates the type or quality of the plastic. The plastic with the lowest number is the easiest to be recycled by the recycling factory, and the one with the highest number are rarely recycled. 
After the plastic container is recycled, the number almost always rises, because the recycling process will reduce the quality of the plastic products.
 consumers can refuse to buy products that are packaged in the highest-numbered affixed plastic products to significantly reduce the long-term non-recyclable waste.