Polystyrene (PS) /ˌpɒliˈstaɪriːn/ is a synthetic aromatic hydrocarbon polymer made from the monomer known as styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and rather brittle. It is an inexpensive resin per unit weight.
“Polystyrene foam is a light weight material that can be blown by the wind out of garbage cans and landfills into storm drains and waterways, creating litter, polluting the water, and potentially causing harm to wildlife who mistakenly eat the material.”
Under ASTM standards, polystyrene is regarded as not biodegradable.