Plastics Part 7: Polystyrene, expanded polystyrene… you know, your foam cup

Guest blogger, Jessica Connolly of Recology San Mateo County explores plastics and her relationship to them in this series.

Polystyrene (PS) is traditionally known by its more widespread name: Styrofoam. PS can be made into a variety of forms such as expanded PS, which is most prevalent, extruded PS, and foam PS, both of which are less ubiquitous.

Expanded PS is about 95% air and 5% plastic. It is what we know as packing peanuts, packing materials, disposable foam cups and food containers. PS is generally more affordable than other disposable products, making it a desirable container choice for establishments that sell food and beverages. Extruded PS is used in disposable food utensils, DVD and CD cases, disposable razors, and those omnipresent disposable red party cups. PS foam is also used as home and building insulation. In that application, it is injected in between walls, whereupon it expands and seals. It is viewed as a lighter and cheaper material to insulate with and is an alternative to concrete.

Src: Wikipedia

Whatever monetary cost savings it may have, PS is not easy to recycle because of its light weight and low scrap value. Just imagine filling a semi-truck with PS; the little value of the material would be erased by the cost to fuel and drive the truck. With that said, however, other forms of PS are accepted in recycling programs because they have a higher density and a higher scrap value. When PS is recycled, it is usually made into coat hangers, park benches, flower pots, toys, and architectural molding.

PS is too light to accept into our single stream recycling program, but at the San Francisco transfer station, we accept it from residents and businesses for recycling. Recology San Francisco operates a special densifier that condenses loose pieces of Styrofoam into ingots, which are recycled into base boards and moldings. However, our experiment is only a small step. 

PS has several environmental impacts. Due to its weightlessness, PS travels easily by wind and water and pollutes the surrounding environment. Bits and pieces are what remain from an originally large piece, and animals mistake the small pieces of plastic for food, which then enters the food chain. Marine litter is extremely common in the Pacific Ocean (as well as the other oceans) and much of this floating plastic is PS.

Also, the properties of PS do not normally allow it to break down in a traditional landfill. Plastic in general does not  biodegrade, and PS is a prime example. Scientific estimates of decomposition time are high, between 10 thousand and 1 million years. But who knows how long it will actually take, since PS was invented a mere 150 years ago. We can only estimate its actual rate of decomposition.

At this point, because of its environmental impacts, perhaps the most important piece of advice would be to avoid the consumption of this plastic. With all the widespread knowledge about its harm, it’s crucial to determine if using this product is worth it, since humankind and the environment suffer from this plastics’ pollution. Now that you have read this and have become aware, what will you do to make a difference?

3 Responses to “Plastics Part 7: Polystyrene, expanded polystyrene… you know, your foam cup

  • Where in San Mateo County can I recycle block styrofoam?

    • Hi Larry,

      Try calling or visiting GB Industrial at 1528 Atlantic Street in Union City, CA. According to, they specialize in #7 (unknown) plastics but also take other items. Payment depends on quantity. Free pick up is available for large commercial accounts, upon request. Styrofoam must be clean: no labels, tape, etc. No black Styrofoam. Place small pieces in clear plastic bag. They take all types of packaging materials for recycle, such as EPS, EPP, EPE, and bubble wraps. Fee charged, depending on volume.


      Good luck!

  • daniella
    7 years ago

    You’ve made some decent points there. I checked on the internet to learn more about the issue and found most individuals will go along with your views on this website.

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