Greenpeace reports that plastics with a number 1 inside the recycling symbol have a reprocessing rate of about 20.9%.

Plastics with numbers 3 through 7 have a reprocessing rate of less than 5%, according to Greenpeace.

Only 4.7% of plastic produced by U.S. households in 2021 was recycled, according to a Greenpeace USA report.

While many consumers participate in recycling, most plastics cannot be recycled in the U.S. due to limitations and restrictions, says Greenpeace. Furthermore, China’s higher standards for accepting recyclables has resulted in less plastic being reprocessed.

In honor of Earth Day, it is important to understand the different types of plastics and their respective reprocessing rates.

There are seven types of plastics commonly found in consumer products, two of which are the most recyclable: PET (symbolized by the number 1) and HDPE (symbolized by the number 2). Plastics labeled with a number 1 have a reprocessing rate of approximately 20.9%, and include soda bottles, peanut butter jars, and other clear plastics. PET stands for polyethylene terephthalate.

Plastics labeled with a number 2 have a reprocessing rate of 10.3%, half of that of number 1. Examples of HDPE, or high-density polyethylene, include laundry detergent bottles, shampoo bottles, and other solid-colored plastics.

Plastics numbered 3 through 7 have a reprocessing rate of less than 5%, according to Greenpeace. It is important to note the different types of plastics since municipalities handle each type differently.

Plastics labeled number 3 are polyvinyl chloride, used to make items such as vinyl records and PVC pipes, while plastics labeled number 4, LDPE (low-density polyethylene), can be used to make bread bags, bubble wrap, cling wrap and more. This type of plastic is often collected separately from plastics labeled 1 and 2, and should not be placed in curbside recycling bins.

Plastics labeled number 5 are polypropylene (PP), commonly used to make yogurt containers and other dairy product tubs. Plastics labeled number 6 are polystyrene (PS), which can be used to make takeaway containers, coffee cups, insulation, and disposable coolers. Styrofoam, a commonly used term for this type of plastic foam, is the brand name of DuPont’s polystyrene.

Finally, plastics labeled number 7 are a mixture of various types of plastics.

Correction: A previous version of this story incorrectly named an earlier owner of the Styrofoam brand. The current owner is DuPont.